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Current inputs, Voltage inputs, Unused inputs – Watlow MLS User Manual

Page 53

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Installation

MLS User’s Guide 41

Current Inputs

To install current (milliamp) inputs, place resistors in the input section
which convert the milliamp input into a voltage. (You can get different
current input ranges if you select different resistor values.) The input
connections for these inputs are the same as the input connections for
voltage inputs.

Voltage Inputs

Connect the + side of the voltage input to the A+ terminal. Connect the -
side of the input to the A- terminal. The voltage input range is -10 to 60
mV. Scale signals larger than 60 mV with a scaling resistor which makes
full scale input 60 mV.

The next figure shows two resistors. RA and RB are not loaded. RC is
the voltage reducing or current limiting resistor, and RD is the 60 mV
full scale dropping resistor. RD is normally less than 500 ohms, and it
should never exceed 1000 ohms.

Unused Inputs

Set the input type for unused inputs to "SKIP" to avoid the default T/C
break alarms.

Red

Black

100 Ohm RTD

IN +

IN

Analog Common

Black

Rear Terminal Block
Connections

RD

IN +

IN

To

RC

Circuitry