6 voltage inputs, 7milliamp inputs, 8thermocouple inputs – Watlow 12LS Controller User Manual

Page 26

3-12

3.3.6 VOLTAGE INPUTS

DC Voltage inputs should be connected with the positive side to the CH +IN terminal and the negative side to one of
the -IN COM terminal. The input range is -10 to +60 mv. Signals greater than 60 mv must be scaled with resistors to
match the input full scale to 60 mv. The scaling resistor RA is selected as the voltage dropping and/or current limiting
resistor. RB is selected for the 60 mv full scale dropping resistor. It should normally be less then 500 _ and should
never be greater then 1000 _. Any value above 1000 _ for RB will cause error due to the upscale burnout circuit.
|------------------------------------------------------------------|
¦ TABLE 3-1. TYPICAL STANDARD VALUE SCALING RESISTOR ¦
|------------------------------------------------------------------¦
¦ Output Voltage Range ¦ RA ¦ RB ¦ Accuracy ¦
+------------------------¦----------¦----------¦-------------------¦

¦ 0 - 100 mV ¦ 499

Ω ¦ 750 Ω ¦ + .1 % ¦

¦ 0 - 500 mV ¦5.49 K

Ω ¦

750

Ω ¦ + .1 % ¦

¦ 0 - 1 V ¦6.91 K

Ω ¦

442

Ω ¦ + .2 % ¦

¦ 0 - 5 V ¦39.2 K

Ω ¦

475

Ω ¦ - .2 % ¦

¦ 0 - 10 V ¦49.9 K

Ω ¦ 301 Ω ¦ - .1 % ¦

|------------------------------------------------------------------|+

The above values are standard metal film values and will give an accuracy of +0.25% when using .1% tolerance
resistors. Any possible error due to resistor tolerance may be corrected by using the built in linear scaling.

3.3.7MILLIAMP INPUTS

Current inputs from transmitters are accommodated by placing resistors in the input section to convert the current input
into a voltage. The input connections are the same as the voltage inputs. Different current input ranges are
accommodated by selecting the proper resistor values.

A single 0.1% resistor is used as follows:

4 to 20 ma 0 to 10 ma
RB = 3.000

Ω RB = 6.000 Ω

3.3.8THERMOCOUPLE INPUTS

All thermocouple types may be directly connected to the ANAFAZE 12LS. Types J,K,T,R, S and B linearization
and cold junction compensation are provided standard in the ANAFAZE 12LS. For other thermocouple types, optional
input ranges are required. Thermocouples should be connected with the positive lead to the CH +IN terminal and the
negative lead to one of the -IN COM analog grounds.

Use 20 gage or smaller T/C Extension wire as there are only four terminals for the common negative input lead for 12
loops.