HoneywellControlEdge HC900 Controller Specifications 51-52-03-31, January 2022

Overview

The Honeywell ControlEdge HC900 Controller is an 

advanced loop and logic controller offering a modular 

design sized to satisfy the control and data management 

needs of a wide range of process equipment. When 

combined with the optional 900 Control Station operator 

Interface that is highly integrated with the controller’s 

database, configuration and setup time is minimized. This 

powerful combination together with Honeywell’s 

performance proven control technology provides users an 

ideal solution for process control. Open Ethernet 

connectivity with Modbus TCP Protocol also allows network 

access using a variety of HMI/SCADA software. Program 

execution environment is protected using an independent 

watchdog timer.

Easy-to-use Windows-based Designer software, operable 

over Ethernet or RS485 port (isolated) simplifies controller 

configuration. The software is available in English, Chinese, 

Russian, and German language version. It provides 

advanced monitoring functions for debug, allows run-mode 

process configuration changes while maintaining process 

control, uploads the complete, annotated graphic controller 

configuration, plus supplies an array of reports for 

enhanced documentation. The ControlEdge HC900

Controller provides superior PID loop control and more 

robust analog processing than most logic controllers without 

compromising logic performance. A separate, fast scan 

cycle executes a rich assortment of logic and calculation 

function blocks. Logic blocks may also execute in the same 

scan with analog function blocks for time critical events. 

These function blocks may be fully integrated into a 

combined analog and logic control strategy for 

uncompromising control performance. 

For more information see specification sheets:

• ControlEdge 900 Platform Modules

Specs 51-52-03-41

• Designer Software Specs 51-52-03-43

Applications

Mining & Metals Furnaces, Kilns, Boilers

Chemicals, Extruders Autoclaves

Pharmaceuticals Sterilizers, Dryers

Rail/ Infrastructure Burner Management, 

HVAC/ DataCenters Combustion Control

Pulp & Paper Emergency Shutdown

Cement & Glass Pipeline Monitoring,

Power Spill Prevention

Features Summary

• Supports Split Rack Redundancy

• Supports Honeywell FDM (Field Device Manager) 

using HART IP

• Supports HART function blocks (Command 3 and 48)

Note: UIO Module is required for HART support

• Non-redundant and Redundant Architectures

• Sequence of events support (SOE)

Note: Supported only in non-redundant UIO

configuration.

• Redundant and Non-redundant Safety Universal IO

• PID Control with advanced Accutune III auto-tuning

• Safety peer communication between ControlEdge

HC900 controllers

• External watchdog timer with independent clocks 

that detect spurious CPU lockups

• Adjustable recipe pool memory lets you allocate 

memory for recipes, SP Profiles, sequences and 

schedules to meet your needs

• Up to 4608 points with remote I/O

• Boolean Logic programming. Robust assortment of 

over 100 algorithms

Features Summary, continued ..

• Advanced Floating Point Math Functions.

• Extensive alarm and event monitoring

• Up to 2304 galvanically Isolated, Analog Inputs

• Up to 1008 redundant UIO points

• New I/O voting and output validation function 

blocks.

• Remote I/O Racks with wire for extended 

distance. 

• Star or Ring topology on IO network using 

recommended switches

• Scanner and I/O Insert/Remove under power

• LED on/off indicators on digital I/O

• Graphic Function Block Configuration 

• Open 10MB or 10/100MB Ethernet interface using 

Modbus/TCP. Peer-to-peer communications via 

Ethernet

• E-mail alarm/event messaging on priority

• Ramp/Soak Setpoint Programmers

• Setpoint Schedulers with multiple outputs

• Sequencers with 16 Outputs each

• Modbus read/write parameters assignable to either 

fixed or custom addresses for access by HMI or 

supervisory software.

• Modbus TCP Initiator

• Gas flow function blocks per American Gas 

Association specs. (non-Safety configurations 

only).

• Calendar block for triggering events

• Non-interfering process/safety worksheets capable 

of handling process and safety configurations.

• Built in Version Control

• Fast updates - 10 ms digital and UIO (900U02-

xxxx) 100ms analog capable 

Note: Low Level AI updates @ 0.5 sec.

ControlEdge HC900 Controller

• The rack based ControlEdge HC900 Controller is 

available in 4 rack sizes with 1, 4, 8 or 12 I/O slots 

each to support a wide range of requirements. 

• Redundant C75 controllers use a separate controller 

rack for CPUs without local I/O. Two power supplies 

provide separate CPU power. 

A redundant controller switch module provides status 

and performs mode changes.

CPU Modules

• The CPU options available for the ControlEdge

HC900 Controller include:

▪ C30 and C50 for non-redundant applications.

▪ C70 for dual networking.

▪ C75 for redundant CPU applications and dual

networking. 

▪ All ControlEdge HC900 CPU modules are based on the 

e300 32 Bit RISC based PowerPC Architecture. The 

controller operates out of a battery-backed DDR2 64MB 

memory for C30 and C50 modules, 128MB for C70 and

C75 modules. DDR2 memory on all modules is 

supported with ECC circuitry to enhance reliability and 

error detection.

Program execution environment is protected using an 

independent watchdog timer.

• All ControlEdge HC900 CPU modules offer open Ethernet 

communications for access by a variety of HMI and 

SCADA software applications and peer to peer 

communications for control data exchanges between 

controllers. The C70 and C75 provide dual Ethernet ports 

for high network availability installations.

• ControlEdge HC900 CPU modules use a dual scan 

method to handle fast digital scanning and normal analog 

input scanning in the same integrated control 

environment. Both scans support a wide range of 

computational function block algorithms and a user 

adjustable execution sequence order.

ControlEdge HC900 CPUs use Flash memory for 

permanent user configuration program storage 

and battery-backed memory for dynamic data 

storage allowing for graceful recovery following a 

power interruption or other discontinuous 

operations. Using proven TL5903 primary 

batteries to support up to 24 days of continuous 

power outages

• 5000 SOE event buffering capability

I/O Scanners

ControlEdge HC900 Remote I/O is processed and 

communicated to the main CPU module through a 

remote I/O Scanner module. Two I/O scanner modules 

are available: a single port model for non-redundant 

CPU systems and a dual port model for redundant 

CPU systems. Scanner addressing in multi-rack 

systems is selectable via DIP switch setting.

Program execution environment is protected using an 

independent watchdog timer.

Inputs and Outputs - A variety of I/O modules are 

available for selection in creating a custom control 

solution. These include:

• 8-point universal analog input modules: Inputs 

may be mixed on a module and may include 

multiple thermocouple types, RTDs, ohms, 

voltage, current or millivoltage types – all easily 

assigned using the Designer configuration tool.

High point-to-point isolation simplifies installation 

and saves the expense of external isolation 

hardware. 

• 16-point high level analog input module: each 

point is configurable for V or mA. Point-to-point 

isolation.

• 4-point galvanically isolated analog output 

module: Supports from 0 to 20mA each.

• 8-point analog output module. Galvanically

isolated in two groups of 4. Supports 0 to 20mA.

• 16-point (14-point for redundant configuration) 

Universal I/O module galvanically isolated Input/ 

Output to chassis. Each point can configured as 

DI, DO, AI or AO.

• 16-point digital galvanically isolated AC/DC input 

module.

• 16-point analog output module. Galvanically isolated in 

four groups of 4. Supports 0 to 20mA.

• 16-point digital galvanically isolated input modules: 

Contact closure type, DC voltage and AC voltage types.

• 32-point galvanically isolated digital input (sink) module: 

DC voltage

• 8-point AC or 16 point galvanically isolated DC digital 

output (sink) modules

• 32-point galvanically isolated digital output (source): DC 

voltage

• 8-point galvanically isolated high voltage

• 8-point galvanically isolated relay output module: four 

form C type and four forms A type relays.

• 4 channel Pulse/ Frequency/Quadrature I/O module

See Module Specifucation sheet 51-52-03-41 for details.

Insert & removal of I/O under power - For ease of 

maintenance, the ControlEdge HC900 controller supports 

removing and inserting modules from the card rack without 

removing power from the controller. Each card is sensed for 

validity by the controller and auto-configured on insertion.

Hardware can be replaced without shutting down operations 

for replacement of CPU or Scanner modules thus reducing 

downtime and total cost of ownership.

I/O Terminal Blocks – 20-screw Terminal Blocks 

are available with either barrier style or Euro style screw 

connections. A module label area is provided for field wiring 

identification. An available 36-screw Euro Terminal block is 

required for certain high capacity modules. 

Remote I/O - I/O racks may be remotely mounted 

from the controller via a dedicated Ethernet 10/100Base-T 

connection at up to 300 meters (984 feet) between the 

controller and the most remote rack using two Ethernet 

switches. Use of fiber optic cable extends distance to 40 

Kilometers.

Remote Terminal Panels - Optional DIN rail mounted 

Remote Terminal Panels (RTPs) are available for use 

with pre-wired cables to reduce installation time and 

labor expense. RTP types available: analog input, 

relay output, discrete input, discrete output, analog 

output.

Three cable lengths are also available to match 

hardware to installation variations. See Module 

Specification sheet 51-52-03-41 for more details.

Redundant Power - A second (backup) power module may 

be added to each ControlEdge HC900 controller rack. An 

extended rack is available that expands the standard 8 and 

12 I/O rack to accommodate a second (redundant) power 

supply and power status module.

Redundant Architectures

Redundant Controller

Two redundant C75 CPUs operate in a separately 

mounted controller rack, each with an independent 

900PS1 model power supply. A Redundant Switch 

Module (RSM) is located in the rack between the two 

C75 CPUs. A key switch on the RSM allows the user 

to change the operating mode of the Lead CPU. There 

is no I/O in the controller rack; the CPUs communicate 

with up to 12 racks of I/O over a 100 base-T Ethernet 

physical communication link or fiber optics with an 

external media converter for greater distance. When 

more than one I/O rack is used in the system, Ethernet 

switches are required, one port for each Scanner 

connection. In operation, all control functions and host 

communication exchanges are handled by the Lead 

controller, including configuration and operator 

changes. The Lead controller updates the Reserve 

controller every scan cycle with all the information 

needed to assume control in the event of a fault 

condition.

After power-up of the C75 CPUs, the first available 

CPU assumes the Lead function. The Lead may be 

transferred to the Reserve controller by:

• Failure of the Lead controller,

• Manually changing a keyed switch located on 

the Redundant Switch Module, 

• Input pin on Redundancy Status function block, or

• Instruction from host communication.

Dual Networks for Host communications are provided on the 

C75 CPU. Both network ports are continuously active on the 

Lead controller. Matrikon OPC server is available from 

Honeywell Matrikon to support dual Ethernet 

communications and automatically transfer communications.

The C75 network ports may otherwise be used in nonredundant mode where only one of the communication ports 

is used.

Remote I/O - To extend the distance between the CPU rack 

and the most distant I/O rack to 300m (984 ft.) up to two 

Ethernet switches may be used in each I/O connection. 

Distances up to 40km are possible with fiber optic cable.

Operator Interface – The 900 Control Station Operator 

Interfaces (900CR series) is supported with the C75 CPU.

An Ethernet connection is made to a switch connected to 

the Ethernet port of each CPU. The operator interface 

communication to the controller follows the Lead controller 

assignment.

Status/Diagnostics - An output parameter of the system 

monitor function block of C75 CPUs provides a digital status 

of the Reserve controller to allow integration of this 

information into the control strategy. C75 CPUs also provide 

diagnostic status on redundancy operation that may be 

observed using Designer configuration software. A 

Redundancy status function block is also available to 

monitor redundant controller operation. 

Function Blocks

A large assortment of analog and digital function 

blocks are available to solve the most demanding 

control requirements. Function blocks are grouped by 

scan rate, fast or normal, and by function, Principal or 

Standard.

Function Block Execution - All function blocks 

operate synchronously with I/O processing. Inputs are 

measured at the start of every scan and outputs are 

updated at the end of every scan. Function blocks 

such as Time Proportioning Outputs (TPO) and 

Position Proportioning outputs (PPO) require higher 

output resolution and are updated when the function 

blocks are executing. Micro-controllers on digital I/O 

modules can maintain TPO duty cycle operation during 

failsafe conditions. Micro-controllers on all I/O modules 

allow outputs to be configured to assume a default 

state in the event of a fault condition.

Normal Scan: Function blocks that execute during the 

Normal Scan are synchronized to the analog input 

measurements. The fastest update rate is 500ms. 

100ms analog capable from version v6.300 and above. 

Note: Low Level AI updates @ 0.5 sec.

Fast Scan: The fastest update rate for fast scan 

function blocks in a single controller rack is 10ms. The 

update rate starts at 25ms when remote racks are 

used and for redundant systems.

Principal Function Blocks – These function blocks 

are supported by dedicated Widget objects in Station 

Designer software for configuring 900 Control Station 

operator interfaces. They have Tag names and other 

attributes to support on-line user interaction. Principal 

function blocks can be used any number of times in a 

configuration.

Typical Principal function blocks include PID, Set Point 

Programming, Sequencers, Alternators, Stage, etc

Standard Function Blocks – The number of standard 

function blocks that may be used in a configuration is 

virtually unlimited. Typical Standard blocks include 

totalizer, free-form math, average, mass flow, function 

generator, periodic timers based on real-time, carbon 

potential, RH, Dew Point, signal selection, comparison, 

gas flow, real time clock, and many others. These 

blocks may be configured to create control schemes 

that precisely address the needs of your process. 

Digital status outputs are also provided on many of the 

analog function blocks to facilitate intelligent signal 

alarming and default operation strategies. 

Typical logic function blocks include AND, OR, XOR, NOT, 

Latch, Flip-flop, On/Off Delay and Resettable timers, 

Counters, Free-form Boolean logic and more. The execution 

of analog and digital functions is seamlessly integrated into 

a single control strategy in the controller. 

AI-V – The new AI-V function blocks will allow 1oo2 and 

2oo3 voting for inputs and compares its values with one 

another and reports any deviation if validation between one 

another fails. Output value is calculated by comparing all 

inputs channels and selecting best of three. 

DI-V - The new DI-V function blocks will allow 1oo2 and 

2oo3 voting for inputs voting for inputs and compares its 

values with one another and reports any deviation if 

validation between one another fails. Output value is 

calculated by comparing all inputs channels and selecting 

best of three.

AO-V – The AO-V block is similar to the AO block but it 

provides additional functionality which allows users to 

validate the status of the output using a feedback input 

channel. The primary function of this block is to validate the 

feedback signal and provides indication when input fails to 

match the output due to possible reasons such as field 

power failure, cable failure, fuse etc. The function block will 

also check the feedback input signal for input module error, 

failed input channel and loss of feedback module 

communications. 

DO-V - The DO-V block is similar to the DO block but it 

provides additional functionality which allows users to 

validate the status of the output using a feedback input 

channel. The primary function of this block is to validate the 

feedback signal and provides indication when input fails to 

match the output due to possible reasons such as field 

power failure, cable failure, fuse etc. The function block will 

also check the feedback input signal for input module error, 

failed input channel and loss of feedback module 

communications.

Alarms/Events

Alarms and events represent changes in digital status that 

require user notification. The ControlEdge HC900 controller 

supports an internal alarm annunciation system that may be 

setup to operate via e-mail to a remote computer (see 

Communications, E-mail Alarming). Up to 360 alarm points 

per controller may be grouped in 30 groups of 12.

Events are digital status changes that cause messages to 

be presented on the 900 Control Station operator interface. 

Controller events may prompt e-mail messages, 

do not require acknowledgement, and are reported and 

logged in a separate group. Up to 64 event points are 

supported in a controller.

Alarms and events are time stamped in the controller to a 

one second resolution.

Sequence of Event (SOE)

SOE is a mechanism for recording and determining the 

order (sequence) of digital state changes (on DI 

channel). High-resolution SOE uses 1 msec time 

stamping. SOE display tool (historian or control station) 

shall map the SOE event properties from signal 

number in configuration file.

Note: 

• SOE is supported only in non-redundant UIO

configuration.

• As of now SOE events across controllers may not be 

correlated properly as there is no time sync across 

controllers

Configuration

Controller configuration is performed using Designer 

Configuration software on a PC operating with 

Windows™ 7 (32-bit and 64-bit), Windows™ 8.1 (32-bit 

and 64-bit), Windows™ 10 (32-bit and 64-bit), Windows 

Server 2016, and Windows Server 2019. Configuration 

files are built independently on the PC and downloaded to 

the controller in a separate operation. 

Validation of proper physical I/O to support the 

configuration is provided along with appropriate warnings. 

Configuration Back-build - In the event a PC 

configuration file is lost or misplaced, it can be easily 

reconstructed using the upload function of the Designer 

configuration software. Simply read the configuration 

from the controller to exactly duplicate the original 

configuration, including all text descriptions. 

Configuration edit - In the event edits to a controller’s 

configuration are required after the unit is in operation, an 

uploaded file may be monitored during process operation, 

edited, and downloaded with the on-line download function 

of the Designer. The software allows configuration changes 

while in the Run mode, limiting process disturbances.

Note: Forcing and downloads cannot be made on Safety 

controllers unless they are switched to the RUN/PROGRAM mode.

I/O Redundancy

CAUTION: For I/O redundancy, prefabricated cable length 

from RTP to Redundant UIO modules must be same.

• Flexibility in configuration

• I/O Redundancy RTP (Model No – 900RTI-0100)

Recipes

Recipes are groups of data defined by the user that are 

used to make multiple value changes in the controller 

through a single action. Function block types that accept 

recipe data and the quantity of recipes stored in the 

controller are listed in Table 2.

Recipes may also include Variables, which are dynamic 

analog and digital values used as inputs to standard and 

principal function blocks. Recipes may be loaded through 

the 900 Control Station operator interface by name or 

number, or via a dedicated recipe load function block and 

user configured logic.

Operator Interfaces

A ControlEdge HC900 controller can support up to three 

900 Control Station operator interfaces via Ethernet or 

Serial communications. The interface is configured with 

Station Designer software using a database 

import function to simplify the setup. See specification 

sheet 51-52-03-102 for more information on this 

interface.

Note: The old phased-out Control Stations (900CS10-

00/ 900CS15-00) will not support import of HC900 

software configuration file (*.cde) v7.1 and above. For 

HC Designer v7.1 and above please migrate to new

900CR series Control Stations with Station Designer 

v3.1.7100 and above.

Communications

HART IP – The HC900 controller supports industry 

standard HART (Highway Addressable Remote 

Transducer) protocol to integrate with asset manager 

(Currently it is qualified with Honeywell FDM).

HART supports two functionalities:

• HART IP client (FDM) communication

• HART Function Block communication

The controller enables the HART IP client to exchange 

information with HART field devices connected to the 

Al/AO channels in the controller via a HART-IP Server. 

Multiple HART IP clients can be served by the 

controller at the same time. When the HART IP client 

builds a HART command request and sends it to the 

TCP/IP port of the HART-IP server, the HART-IP 

server responds to the HART IP client with information 

from the field device. Since it takes time for the 

controller to communicate with the field devices 

through onboard or remote I/O cards, a delayed 

response mechanism is implemented. The TCP /IP 

port of the HART-IP server is user-configurable and 

the default port number is 5094. The end user may 

change the port number if firewall configuration is 

required.

The controller enables HART function blocks to access 

to the HART field devices through HART-enabled 

Al/AO channels. Currently HART command 3, 

command 48 and command X are implemented.

Remote I/O Rack Port (C50, C70, C75) – An Ethernet 

port is dedicated to supporting remote I/O racks. This 

10/100Base-T Connection on the C50 and C70 CPU 

supports a single direct connected remote rack or up 

to 11 remote racks when connected through an 

external Ethernet switch. The C75 CPU supports a 

single direct connected rack or up to 12 remote racks 

using external switches.

User Interface Support – The 900 Control Station interface 

may be connected via Ethernet or serial communications. Up 

to three interfaces may be connected to a controller for 

distances up to 328 feet (100Meters) via Ethernet or 2000 

feet (609 meters) between the controller and operator 

interface. 3rd party user Interface support is provided through 

an isolated RS485 port connection using Modbus/RTU 

protocol, or Ethernet with Modbus/TCP protocol.

Ethernet Modbus/TCP Communications –

ControlEdge HC900 controllers communicate with their host 

PC interfaces over an Ethernet 10/100Base-T communication 

network using the Modbus/TCP protocol, an open protocol 

interface available for most popular HMI software packages. 

The controllers Ethernet ports are MDIX and configured to 

auto negotiate and will default to half duplex if host fails to 

negotiate. The C30 supports up to 5 host connections while 

the C50/C70/C75 support up to 10 concurrent host 

connections over an Ethernet network for control supervision 

and data acquisition. The Designer software can also address 

any of the controllers concurrently over Ethernet for 

configuration monitoring, diagnostic interrogation, upload/ 

download, or on-line configuration changes. As a result, a 

ControlEdge HC900 network of controllers and operator 

interfaces can be partitioned into process segments to assure 

proper control performance. Each of these process segments, 

in turn, can be accessed via common HMI software within the 

plant environment using an Ethernet LAN.

Ethernet Peer to Peer Communications - Peer data 

communications between one ControlEdge HC900 controller 

and up to 32 other ControlEdge HC900 controllers is 

supported over Ethernet via UDP protocol for safety/process 

data sharing. Both digital and analog data exchange are 

supported using peer data exchange function blocks, up to 

2240 (max 44 peer writes per modbus device) parameters 

between peer controllers. For SIL variants the safety peer 

function blocks can be used for Safety peer communication 

along with peer data exchange function blocks. No 

specialized software is required. Peer data can be given 

signal tag references for use in a control or data acquisition 

strategy. Peer to peer data interchange does not consume 

one of the host connections.

Serial Modbus RTU Communications - Serial Modbus 

RTU communications is available on the isolated RS485 (2 

wire) ports of the ControlEdge HC900 Controller CPU 

assembly in a Modbus Host or Device mode. The protocol of 

these ports is user selectable between ELN protocol for use 

with HC Designer software or Serial Modbus to interface 

with other compatible devices. 

Modbus RTU Device - Isolated RS485 ports

may be configured for simultaneous operation as a 

Modbus device port to allow each to communicate with 

a single Modbus host. 

The Modbus protocol supports read and write access 

to a default address map of certain function blocks and 

parameters.

In configurations 4.0 and later, a map of customized 

addresses, blocks and parameters can be created 

either by editing the default map or from scratch.

In the default map (fixed), a 4000 register array is 

available to allow the user to specify the address 

locations of specific controller data to optimize 

controller communications.

The data in the array may also be accessed in user 

specified formats (data types) such as analog data in 

Float 32, unsigned 16, signed 16, unsigned 32, signed 

32, and digital data in signed 16 or unsigned 16.

The data type selections in the 4000 register array 

provide compatibility with devices such as 3rd party 

touch panels. In the custom map, all data formats are 

adjustable.

Modbus RTU Host - Either of the ports may be 

configured as a Modbus RTU host, one per controller.

Up to 32 devices may be multi-dropped on the isolated 

RS485 port. Function blocks are available in the 

ControlEdge HC900 controller to allow the user to 

specify read and write operations to up to 32 external 

Modbus compatible modus device devices and up to 

1024 data points.

Modbus TCP Initiator – The Ethernet ports may be 

configured as a Modbus TCP initiator. Function blocks 

are available in the ControlEdge HC900 controller to 

allow the user to specify read and write operations to 

compatible modbus device devices for up to 1024 data 

points.

Profibus – The ControlEdge HC900 can access data from 

Profibus modbus device devices using a Modbus-toProfibus gateway device attached to the serial port of the 

controller. The gateway device is a Profibus Host on the 

fieldbus network and a Modbus device to the ControlEdge

HC900. The Profibus data is connected into the control 

strategy using Modbus function blocks. This application has 

been validated with a ProLinx 5104-MCM-PDPM gateway 

(from ProSoft® Technology).

E-mail Alarms/Events--ControlEdge HC900 alarms or 

events can be individually configured to send an e-mail 

alarm (or event) message to e-mail addresses with the 

assigned alarm priority.

• Number of e-mail addresses: 3 based on alarm 

priority

• From: Controller name (up to 16 characters)

• Subject: text (up to 32 characters)

• Content: date and time of alarm/event, alarm/event 

tag name, alarm/event state

• Message: 48 character text (for alarms only)

• Priority Levels: 4 for alarms, 1 for events

Controller Configuration Access –Designer software 

supports communicating with ControlEdge HC900

controllers using an Ethernet or serial connection using ELN 

protocol to support direct PC connection for configuration 

upload, download, debug and maintenance. Modbus RTU 

protocol is also supported through the serial port interface.

Once the ControlEdge HC900 controller has been 

configured using Designer Software, on-line configuration 

changes 

may be made while maintaining process control. 

Configurations may also be loaded into the controller via the 

Ethernet TCP/IP network from a host PC. On-line monitoring 

for program debug and on-line program edit functions are 

also supported via the Ethernet port.

Modem Access – Communications to the 

ControlEdge HC900 controller may be via an external 

modem connected to the controller’s using an 

RS485/RS232 converter. HC Designer software 

supports configuration upload, download and on-line 

edits via modem. When modem communication is 

selected, Modbus RTU communication timeouts are 

extended.

Experion Supervisory Software – Honeywell’s 

Windows 10 version is available when PC-based 

supervisory control and data acquisition is required. 

Ethernet network interface to an Experion server is via 

the controller host Ethernet 100 Base-T port using 

Modbus/TCP protocol. Client Stations over Ethernet 

allow multiple user access to a ControlEdge HC900

network. Using the large selection of standard 

operating display templates in Experion saves 

development time. When further customization is 

needed, the full graphic display development 

environment of Experion may be used to fully animate 

your process supervisory displays. 

A batch reporting option is offered in Release 500 and 

430 which enables batch reports to be created using a 

standard template. User-entered lot data is supported 

and up to 50 parameters can be defined for batch 

logging. The file can be exported in .csv format using a 

lot number-encoded filename.

SpecView32 Supervisory Software – SpecView32 

software can be used as a supervisory interface for 

thermal-based applications, offering historical trending, 

batch reporting, recipe development involving setpoint 

programs and simplified graphics configuration. 

ControlEdge HC900 parameters are simply selected 

from categorized lists for placement on userconfigured displays or onto display objects.

Network connection is via the controller host Ethernet 

10/100Base-T port using Modbus/TCP protocol. A 

variety of Windows operating environments are 

supported.

OPC Server – Network communication access to 

ControlEdge HC900 controllers through third party PC 

interfaces is simplified with Honeywell’s Matrikon OPC 

server software program. This software supports the 

Modbus/TCP interface to either redundant or non-redundant 

ControlEdge HC900 controllers. In redundant applications, 

Matrikon OPC Server software supports dual Ethernet 

connections to both C75 CPUs. Communications to the 

controller is maintained during a single network failure 

and/or following the transfer of the Lead function from one 

CPU to another. Compatible OPC client programs can use 

the Ethernet connection to the ControlEdge HC900 via 

Honeywell’s OPC Server for remote supervision, data 

collection or other supervisory functions.

Capacity

The capacity of the ControlEdge HC900 system is 

determined by the type of CPU selected, the quantity 

of I/O racks, the quantity’s type of I/O modules, the 

update rate (scan rate) required, and CPU memory. In 

most applications, the CPU memory limit has a low 

probability of limiting capacity. 

How many I/O channels?

Number of I/O is limited only by physical space. 

Namely, the number of racks, the number of modules 

per rack, and the number of channels in the modules.

In general, 

Maximum I/O channels = (max. number of I/O racks) x

(max. number of modules in each rack) x

(max. number of channels per module)

Examples

Maximum C30 I/O = 1 rack x 12 modules x 32 

channels per module = 384 I/O channels

Maximum C50, C70, C75 I/O = 12 racks x 12 modules 

per rack x 32 channels per module = 4608 I/O channels.

Maximum C75 Redundant UIO = 6 Redundant racks 

(12 racks) x 12 modules per rack x 14 channels per 

module = 1008 I/O channels.

How many function blocks (loops, programmers, 

etc.)?

Fixed limits are not imposed on function block types. 

Your configuration can probably contain as many of 

each function block as needed. The limit is reached 

when either

a) Dynamic memory is full or

b) Maximum function block quantity is reached or

c) Configuration memory is full or

d) Over 65,535 block configuration parameters or 

block inputs used (but not Block Outputs).

These limits are explained below.

a) Dynamic Memory

The rule of thumb is: Max. number of function blocks =

Dynamic memory ÷ memory per function block

The smaller the function block, the more of them can fit 

in your configuration.

b) Quantity

Memory limitation is not for function blocks.

Complex blocks such as PID, Programmer, and 

Scheduler Sequencer use more memory than simpler 

blocks like On/Off, Device Control, Auto/Manual Bias. 

For example, several thousand Auto/Manual Bias 

blocks would fit in the C30’s memory if not for the quantity 

limit of 400. 

Conversely, about 300 Scheduler blocks will consume all 

the C30’s memory despite the higher quantity limit of 400.

Scan Time Consideration

Another consideration when configuring function blocks is 

scan time and the potential for CPU scan time to become 

insufficient for the application.

The scan time of a controller increases in fixed increments. 

As function blocks are added to a configuration, the time 

needed to execute the total configuration is recalculated. If 

additional time is needed, the scan time will be increased to 

the next increment in sequence. (See Specification section 

for scan time increments)

How many recipes in my pool?

Unlike with function blocks, there is no quantity limit to 

recipes. The only limiting factor to recipe pool size is 

available memory. Whatever memory is unused by the rest 

of your configuration (that is, function blocks) can be 

allocated for recipes. As long as memory is available, 

allocate as many recipes as needed. 

The rule of thumb is 

Max. number of recipes = Recipe memory allocation ÷

memory per recipe

Configuration memory allocation

The configuration memory comprises one allocation for the 

function block configuration and one allocation for recipes. 

In general,

Total configuration memory = 

Configuration + Recipe allocation

Whatever memory has not been allocated to recipes is 

available for your configuration. By changing the size of the 

recipe pool allocation, you control the amount of memory 

available for recipes and therefore configuration. Need a 

small configuration but many recipes? Allocate more recipe 

space. Need a large configuration but few recipes? 

Allocate less recipe space

Where are usage/capacities presented?

File Properties in Designer displays statistics on 

usage/availability of:

• configuration memory (recipes + function 

block configuration), 

• dynamic memory (function block configuration 

only)

• fast scan time,

• Normal scan time,

• Normal CPU% used,

• Fast CPU% used,

• Each component of a configuration (variables, 

constants, etc.).

Controller Data Storage

The controller may log process data values in the available 

memory that is not used by the configuration. Up to 250 

signal values may be logged in a rotating buffer using three 

different sample rates with oldest data being replaced with 

new data after the buffer is full.

Data is extracted from the controller using HC Historian data 

harvesting software via Ethernet or Serial connection.