Omega DRA-CSM-1 Quick Manual

DRA-CSM-1

CURRENT MULTIPLEXER

User’s Guide

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Contents

1. GENERAL DESCRIPTION

2. MOUNTING INSTRUCTIONS

3. REPLACING FUSES

4. ASSEMBLY

5. SUPPLY VOLTAGE

6. CONNECTING TRANSMITTERS TO THE MULTIPLEXER

6.1 Two-Wire Transmitter

6.2 Three-Wire Transmitter

6.3 Four-Wire Transmitter

7. CONTROL

7.1 Enable/Test

7.2 Address

7.3 Address Polarity

7.4 Control Tables

7.4.1 True Low Setting

7.4.2 True High Setting

8. MULTI-DROP CONFIGURATION

9. SPECIFICATIONS

1

1.GENERAL DESCRIPTION

WARNING: Never connect a voltage source as an input to the
multiplexer. Its internal low dynamic impedance
will cause immediate fuse blowing.

3. REPLACING FUSES

2. MOUNTING INSTRUCTIONS

2

The DRA-CSM-1 is a multiplexer for 16 analog 4-20mA current loops.
The transmitter/transducer currents are input via "I" terminals. Each input is

protected by a 63mA fuse.
The current input is steered either to the output ("lo") terminal or to the negative

(COM) terminal of the power supply (PWR). Fifteen channels are routed to the
COM and only the selected one is routed to the output terminals, thus ensuring
a continuous and uninterrupted current loop.

The multiplexer's channel selection is controlled by 4 address lines, generated by
the PLC's discrete output module.

The unit provides 16, current limited (~40mA), voltage supply ("V") outputs. These
outputs are derived from the mux's power supply input and are used to feed two­wire transmitters. The current limitation avoids fuse blowing in cases of short­circuit of the transmitters' leads.

The DRA-CSM-1 is designed for standard DIN rail mounting.
Place the unit on the upper part of the mounting rail with the fastening tab facing

down. Loosen the tab slightly, using a suitable flat screwdriver, and attach the unit
to the rail. After releasing the tab, make sure that the unit is fastened securely in
place.

To replace a blown fuse, disassemble the unit as follows:
a. Take off both terminal strips by removing the four screws at the edges.

Note: This does not require disconnecting the cables connected to the strips.

b. Remove the front panel using a suitable flat screwdriver. Press down gently on
the plastic springloaded tabs located in the slots on either side of the unit.