WATLOWCompact Loop System, Providing Powerful Control in a 1 /8 DIN Package

• 16-loop model: 16 single-ended inputs

Analog Over Voltage Protection

• ±20V referenced to digital ground

Maximum Common Mode Voltage

• 5V input to input or input to analog common 

(4- and 8-loop models)

Common Mode Rejection (CMR)

• For inputs that do not exceed ±5V, >60dB dc to 1kHz and 

120dB at selected line frequency 

Noise Rejection 

• 120dB at 60Hz

Sensors/Inputs

• Thermocouples: user-selectable type, direct connection, 

linearization, reference junction compensation, reversed 

and shorted thermocouple detection and upscale break 

protection with output averaging 

• RTD: (4 and 8 loop models only) 2- or 3-wire, platinum, 

100Ω @ 0°C, DIN 0.003850Ω/Ω/°C curve, user-selectable 

range. Two ranges offer different resolutions. Requires 

scaling resistors. See ordering information.

• Linear: current and voltage signals from linear transmitters 

• Pulse input

Input Range and Accuracy 

Sensor Range (°C) Range (°F) Accuracy

Type B 66 to 1760°C 150 to 3200°F ±4.0°C

Type E -200 to 787°C -328 to 1448°F ±1.0°C

Type J -212 to 760°C -350 to 1400°F ±1.2°C

Type K -268 to 1371°C -450 to 2500°F ±1.3°C

Type R -18 to 1766°C 0 to 3210°F ±2.8°C

Type S -18 to 1760°C 0 to 3200°F ±2.8°C

Type T -268 to 399°C -450 to 750°F ±1.6°C

RTDs available on CLS204 and CLS208 only.

Sensor Range (°C) Range (°F) Accuracy

RTD1 -100 to 275˚C -148 to 527˚F ±1.1˚C

RTD2 -120 to 840˚C -184 to 1544˚F ±1.6˚C

Note: Accuracy @ 25˚C ambient. Valid for 10 to 100 percent 

of span except Type B, which is specified for 800˚F to 

3200˚F. RTD.

Linear Voltage and Current Inputs

Requires scaling resistors. See ordering information.

0-20mAVDC/4-20mAVDC

0-5VDC

0-10VDC

Temperature coefficient: 40ppm/°C

Other ranges available. Contact factory. 

Pulse Input 

• One TTL-level square wave input up to 2kHz

Input Sampling Rate at 60Hz 

Each channel has the following scans per second:

• 4-loop model: 6 samples per second, 

(update time: 0.167 sec.)

• 8-loop model: 3 samples per second, 

(update time: 0.333 sec.)

• 16-loop model: 1.5 samples per second, 

(update time: 0.667 sec.)

Internal Measurement Resolution

• 0.006 percent, greater than 14 bits

Calibration

• Automatic zero and full scale

Digital Inputs 

• TTL-level used for selecting recipes or jobs, or R/S triggers

• 8 digital inputs and 1 pulse input with mass termination 

(SCSI) digital I/O termination and TB50 terminal board 

options

• 2 digital inputs and 1 pulse input with screw terminal 

(TB18) digital I/O termination option

Digital Outputs

• 34 digital outputs with mass termination (SCSI) digital I/O 

termination and TB50 terminal board options

• 11 control and alarm outputs with screw terminal (TB18) 

digital I/O termination option

• 1 or 2 control outputs are user assigned for each loop

• Each control output can be configured for on-off time 

proportioning, or distributed zero crossing

• Outputs sink up to 60mA each at 5VDC

• 350mA at 5VDC available from on-board supply 

Alarm Outputs 

• Independent process and deviation alarms for each 

channel

• Alarms can operate any output not used for control

• User-programmable deadband, delay and startup 

suppression

• Global alarm output activates when any alarm occurs

• Watchdog output indicates controller is functioning 

correctly

Serial Interface 

• EIA/TIA-232 or EIA/TIA-485 

Baud Rate

• 2400, 9600 or 19200, user-selectable

Communications Protocols

• Form of ANSI X3.28-1976, (D1, F1) compatible with 

Allen-Bradley PLC/2

• Modbus® RTU

Line Voltage/Power

• 15 to 24VDC ± 3VDC @ 1A (maximum),

300mA (no load)

Agency Approvals

• UL®, C-UL® listed: UL®61010-1 safety requirements for 

measurement, control and laboratory equipment

• CE Mark: See Declaration of Conformity for details

• RoHS by design

Ordering Information

Instructions: Choose one option for each feature

Note: To obtain a part number for your choice of options, communicate your selections to your Watlow sales representative who 

will provide a part number to you.