WATLOWMLS300 Series User’s Guide

input scaling resistors, if required. (RTDs, inputs greater than 

60 mVdc, and mAdc current inputs require input scaling 

resistors.) The AIM-TB has three slots for the plug-in AIM 

cards. 

There are two versions of the MLS300-AIM: the AIM-16 and 

AIM-32. The AIM-16 has one multiplexer (MUX) card, and 

the AIM-32 has two MUX cards. These cards multiplex the 16 

inputs each card receives. Each -10 to 60 mVdc input is 

converted to a voltage that is transmitted to the Voltage/

Frequency (V/F) card. (The MUX cards also automatically 

calibrate the zero and span of the analog amplifier and 

measure the cold junction compensation temperature for 

thermocouple inputs.) Both the AIM-16 and AIM-32 have a 

V/F card, which converts the input signal voltage to a 

frequency. The converted signal is then transmitted via the 

AIM cable to the MLS300-PM for processing.

The MLS300 Compact Input Module (CIM300) consists of 

two circuit boards that perform analog-to-digital conversion 

and data communications to the processor module. The 

CIM300 receives input signals from sensors and transmits this 

information to the MLS300-PM through the AIM cable.

The CIM300 includes power supply terminals, input signal 

connectors, a communications connector and input signal 

conditioning circuits. It also includes a cold-junction 

temperature sensor and room for the input scaling resistors, if 

required. (RTDs, inputs greater than 60 mV dc, and mA dc 

current inputs require input scaling resistors.) 

There are two versions of the CIM300: the CIM316 and 

CIM332. The CIM316 supports 16 inputs through a D-Sub 50 

female connector and the CIM332 supports 32 inputs through 

2 D-Sub 50 connectors (inputs 1 to 16 female, inputs 17 to 32 

male). The user supplies the mating D-Sub 50 connectors. The 

CIM300 has one or two multiplexer circuits that multiplex the 

16 inputs each card receives. Each -10 to 60 mV dc input is 

converted to a voltage that is transmitted to the Voltage/

Frequency (V/F) card. (The mulitplexer circuits also 

automatically calibrate the zero and span of the analog 

amplifier and measure the cold-junction compensation 

temperature for thermocouple (T/C) inputs.) A V/F circuit 

converts the input signal voltage to a frequency. The 

converted signal is then transmitted via the AIM cable to the 

MLS300-PM for processing

MLS300 Cabling

Watlow Anafaze provides cables required to install your 

MLS300. 

A 50-pin SCSI cable connects the TB50 to the MLS300-PM. 

The cable connecting the MLS300-PM to the AIM-TB is an 

8-conductor, shielded cable with RJ-45 connectors. 

The cables used to connect the MLS300 to EIA/RS-232 or 

EIA/RS-485 communications are 6-conductor, shielded cable 

with RJ-12 connectors on one end and a DB-9 connector or 

bare wires on the other end.

The pin numbering convention used for communications cables varies between suppliers. See Serial Communications, Cable

Connector Pin Outs on page 62.

Safety

Watlow Anafaze has made every effort to ensure the 

reliability and safety of this product. In addition, we have 

provided recommendations that will allow you to safely 

install and maintain this controller. 

Ensure that power has been shut off to your

entire process before you begin installation

of the controller.

WARNING! In any application, failures can occur. These

failures can result in full control output (100%

power), or the occurrence of other output failures which can cause damage to the controller, or to the equipment or process

connected to the controller. Therefore, always follow good engineering practices,

electrical codes, and insurance regulations

when installing and operating this equipment. 

External Safety Devices

External safety devices should be used to prevent potentially 

dangerous and unsafe conditions upon equipment failure. 

Always assume that this device can fail with outputs full-on, 

or full-off, by the occurrence of an unexpected external 

condition.

Always install high or low temperature protection in installations where an over-temperature or under-temperature fault will present

a potential hazard. Failure to install external

protection devices where hazards exist can

result in damage to equipment and property

as well as loss of human life.

Power-Fail Protection

In the occurrence of a sudden loss of power, this controller can 

be programmed to reset the control outputs to OFF (this is the 

default). Typically, when power is re-started, the controller 

restarts to data stored in memory. If you have programmed the 

controller to restart with control outputs ON, the memorybased restart might create an unsafe process condition for 

some installations. Therefore, you should only set the restart 

with outputs ON if you are certain your system will safely 

restart. (See Process Power Digital Input on page 98).

When using a computer or host device, you can program the 

software to automatically reload desired operating constants