Four channel analog input, Cold junction compensation – Omega Vehicle Security OMP-MODL User Manual

Page 21

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2... OMP-MODL System Base

Using the OMP-MODL

2-12

A terminal strip is provided at one end of the module for the connection of
sensor and signal wiring. The terminal strip can be unplugged for mass
connect/disconnect of the field wiring. Connections are defined in Figure 2...
-8 and details on each of the functions follow.

Four Channel Analog Input

(terminals 1 through 12)

The MLAD-1 module provides four channels of analog input signal
conditioning identical to that provided by the MLIM-1 Module (Chapter 3).
Each of the four channels can be individually programmed for thermocouple,
DC Voltage and DC Current inputs. Hardware configuration switches are
provided on the MLAD-1 circuit board to configure the input channels for DC
current and medium or high level DC voltage inputs.

Refer to the MLIM-1 Module section in Chapter 3 for details on the input
configuration switches, wiring connections and applications of these inputs.

Cold Junction Compensation

(terminals 13, 14, & 15)

Integral to the MLAD-1 is a cold junction compensation (CJC) sensor. This
sensor is a 10 Kohm @25C (Fenwall curve 16) thermistor which is located
by terminal strip header on the inside of the MLAD-1. The CJC sensor
senses the temperature of the terminal strips (Internal Mode) which in turn,
is used in the mV to temperature conversion equation required in
thermocouple measurements. Additionally, the CJC sensor can be used
within a Program Net to monitor the temperature inside the OMP-MODL
enclosure.

ML007

1

2

3

4

5

6

7

8

9

11

10

12 13

14

15

16 17 18

+

-

+

-

+

-

+

-

A

B

C

D

CJC

GPDI

INTERNAL CJC

EXTERNAL CJC

EARTH GROUND

SHIELD

GND

GND

GND

GND

+

-

CHGND

Figure 2... -8: Terminal Strip connections (MLAD-1 Module, end view)

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