Omega DRA-DCC-8 User Manual

User’s Guide

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DRA-DCC-8

DIGIT AL TO 8 CURRENT LOOP CONVERTER

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It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply.
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The information contained in this document is believed to be correct but OMEGA Engineering, Inc.
accepts no liability for any errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient connected
applications.

Contents

1. MOUNTING INSTRUCTIONS

2. REPLACING FUSES

3. ASSEMBLY

4. SUPPLY VOLTAGE

5. MODES OF OPERATION

5.1 0-20 or 4-20mA output current selection

5.2 Switch Settings

6. PARALLEL CONTROL MODE

6.1 PLC Interface

6.2 The "E" (ENABLE) Terminal

7. SERIAL CONTROL MODE

7.1 RS232c / RS422 Select

7.2 RS422 Termination

7.3 Serial Control Switch Settings

7.4 Serial Communication Parameters

7.4.1 Baud Rate Select

7.4.2 ID Code

7.4.3 Command Formats

8. SELF TEST MODES

8.1 Self Test # 1

8.2 Self Test # 2

8.3 Self Test # 3

9. MULTIDROP CONFIGURATION

10. PUTTING THE UNIT INTO OPERATION

11. CALIBRATION

12. SPECIFICATIONS

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1. MOUNTING INSTRUCTIONS

The DRA-DCC-8 is designed for standard DIN rail mounting.
Place the unit on the upper part of the mounting rail with the fastening tab facing

down. Using a suitable flat screwdriver loosen the tab slightly and attach the unit
to the rail. Once the tab is loosened, ensure that the unit is fastened securely in
place.

2. REPLACING FUSES

In order to replace a blown fuse, the unit has to be disassembled, 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 either side of the unit.
c. Disconnect the flat connector which couples the LED circuit on the front panel.
d. Replace the blown fuse.

WARNING: Never install a fuse rated more than 800mA

3. ASSEMBLY

The DRA-DCC-8 unit includes
two printed circuit cards
designated as P.N 7041 and
P.N 7040. The two printed
circuit cards should occupy
the slots in the enclosure
according to fig 1.

Insert the two printed cards into their slots. Connect the flat cable between them.
Connect the front panel flat cable. The panel must be inserted into the grooves on
both sides of the case while pressing down until a distinct "click" is heard. Assembly
is completed by laying the terminal strips in place.

Figure 1

Note: The terminal strips are polarized and must not be placed backwards.

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4. SUPPLY VOLTAGE

The DRA-DCC-8 is powered by a DC power supply at a range of 15-32Vdc. In order
to determine the minimum supply voltage, use the following equation:

Vmin = 8 + Rload(
where:
Vmin is the minimum required supply voltage.

Rload(

Ω) is the maximum output load including the leads resistance.

Ω) * 0.02

Note: If Vmin turns to be less than 15V, the minimum required voltage
should be 15 Vdc.

5. MODES OF OPERATION

The DRA-DCC-8 unit can be operated in several modes, determined by an internal
array of 8 DIP switches as follows:

4-20 or 0-20mA output current mode
Parallel control mode
Serial control mode
Self test mode

5.1 0-20 OR 4-20mA OUTPUT CURRENT MODE

Two current output spans are available: 4-20mA or 0-20mA selected by SW6.
The DRA-DCC-8 receives 12 bits of data which determine the output current value.
A channel data value of 4095 (FFF) is always interpreted as a 20mA output current.
A channel data value of 0 (000) will produce a 0mA output current when SW6
is OFF, or 4mA when ON.

5.2 SWITCH SETTINGS
Parallel Control Mode

MODE

0-20mA
4-20mA

S1 S2 S3 S4 S5 S6 S7
OFF OFF OFF OFF
OFF OFF ON OFF

XXX
XXX

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