ABBAC 800M Controller Hardware

S800 I/O Unit. This physical appearance does not apply to PM891.

Figure 1. Example of an AC 800M Controller (except PM891) with an S800 I/O 

Unit

shows the PM861 processor unit that is part of the AC 800M controller. 

This processor unit is different from PM891.

PM8xx/TP830 Processor Unit – General

Physically the PM8xx/TP830 Processor Unit consists of two basic parts:

• Processor Unit 

(PM851/PM851A/PM856/PM856A/PM860/PM860A/PM861/PM861A/

PM864/PM864A/PM865/PM866) with processor and Power Supply boards.

• Baseplate (TP830), housing the unit termination board.

For the Functional Block Diagram, see Figure 4 on page 35 and

Figure 5 on page 36. The CPU board contains the microprocessor and the RAMmemory, controllers for all built-in communication interfaces, real-time clock, LED 

indicators, INIT push button and a Compact Flash interface.

The main function of the power supply board is to generate isolated, circuit-proof 

+5 V and +3.3 V supplies to the CPU and I/O units. The board also contains optoisolated RS-232C drivers/receivers for the service port, together with a back-up 

battery holder for memory/real time clock, (RTC).

The termination board, housed in the TP830 Baseplate, is where the majority of 

the external connections terminates. The board is grounded to the DIN-rail through 

of the metallic components of the housing. The termination board is provided with 

screw terminals for power supply and redundant power supply monitoring, with 

RJ45 connectors for the control network and serial port, a connector for the service 

port, the electrical ModuleBus and the CEX-Bus.

The 24 V DC supply, connected to the TP830 Baseplate, powers all the units on the 

CEX-Bus and the electrical ModuleBus.

In single CPU configuration, it is possible to connect an S800 I/O cluster directly to 

the built-in electrical ModuleBus plug located on the right hand side of the TP830 

Baseplate.

The processor unit has a communication expansion bus connector located on 

the left-hand side of the TP830 Baseplate. This CEX-Bus provides for extending 

the on-board communication ports with additional communication interfaces

PROFIBUS DP, FOUNDATION Fieldbus H1, FOUNDATION Fieldbus High Speed 

Ethernet and dual RS-232C ports are some examples of unit types available for 

connection to the CEX-Bus. It is possible to use redundant communication 

interfaces, for example PROFIBUS DP. 

Figure 6 on page 38 provides examples of various ways to connect the S800 I/O 

units. It can be seen, at the top right-hand area of Figure 6 on page 38, that one 

cluster (or group) of units (maximum number of units per cluster is 12) is connected 

to the electrical ModuleBus of an AC 800M Controller. However, a further seven 

clusters (each comprising up to 12 units) can be added to the optical ModuleBus, 

thus achieving a total count of 96 units per AC 800M Controller when using only 

the ModuleBus.

To the left on Figure 6 on page 38, there is a PROFIBUS DP segment. This allows 

for a large increase in the numbers of units connected to each AC 800M Controller. 

Here the segment is shown as having an FCI unit (type CI801), connected to the 

PROFIBUS DP network. The use of FCI units allows the selection of units from 

several I/O families.

Figure 7 on page 39 shows another example for I/O units based on a 

FOUNDATION Fieldbus High Speed Ethernet (FF HSE).

For further examples refer to the relevant documentation for the I/O system in 

question.

Connecting S800 I/O units (using the ModuleBus) to an AC 800M Controller 

mounted with a PM851/PM851A processor unit is restricted to, one electrical 

ModuleBus cluster and one optical ModuleBus cluster

PM891 Processor Unit – General

PM891 is a high performance controller, which is capable of handling applications 

with high requirements.

PM891 connects to the S800 I/O system through the optical Modulebus. It can act 

as a stand-alone Process Controller, or as a controller performing local control tasks 

in a control network. 

Two PM891 controllers can function together as a redundant pair, with one PM891 

acting as the primary controller and the other acting as the backup. The backup 

controller takes over the process controller tasks if any hardware error occurs in the 

primary controller.

The control network connectivity is obtained by two built in IEEE802.3 Ethernet 

channels on PM891.

PM891 also provides a communication expansion bus (CEX-Bus) to which a 

number of expansion modules can be connected. These modules offers connectivity 

to a wide range of field bus and I/O systems. In case of a redundant pair, both 

PM891s are connected to the same CEX-Bus and one of them can control the 

modules.

Physically, the PM891 Processor Unit consists of:

• Connector for power supply and status signals (L+, L-, SA, SB).

• DB25 connector for Electrical CEX-Bus.

• External battery connector.

• RJ45 connectors for the two Ethernet channels.

• One Com port.

• Optical Modulebus connector for connection to a maximum of seven clusters,