Rockwell Automation 57C421B Pulsetach Input Module/DCS 5000/AutoMax User Manual

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3Ć3

Step 7.

You may need to add termination resistors to installations

where the twisted pair cable length from the pulsetach to

the module exceeds 200 feet. The resistor value should

be selected dynamically to provide the proper waveform.
See figure 3.2 for typical termination resistor connections.
For 5 VDC inputs, the termination resistors connect

between:

D terminals 12 and 14 (input A)
D terminals 15 and 17 (input B)
D terminals 18 and 20 (input Z).

For 12 VDC inputs, the termination resistors connect

between:

D terminals 2 and 14 (input A)
D terminals 3 and 17 (input B)
D terminals 4 and 20 (input Z).

When a pulsetach is wired for openĆcollector operation,

the termination resistors should be placed as shown in

figure 3.3.

Step 8.

Insert the cable assembly's (M/N 57C372) field terminal

connector into the mating half on the module. Use a

screwdriver to secure the connector to the module.
Note that both the module and the field terminal

connector are equipped with keys" as shown in figure 2.1.

These keys should be used to prevent the wrong cable

from being connected to a module in the event that

connector needs to be removed and then reĆattached

later.
At the time of installation, rotate the keys on the module

and the connector so that they can be connected

together securely. It is recommended that, for modules so

equipped, the keys on each successive module in the

rack be rotated one position to the right of the keys on

the preceding module.
If you use this method, the keys on a particular connector

will be positioned in such a way as to fit together only

with a specific module, and there will be little chance of

the wrong connector being attached to a module.

Step 9.

Check the wiring and be sure all connections are tight.

Step 10. With the pulsetach disconnected from the motor, apply

power to the rack and the pulsetach. Use an oscilloscope

to test the signal from the pulsetach. The signal at the

terminal strip should be a clean square wave of 5 or 12

volts.

Step 11. Verify the installation using the Programming Executive

software. Refer to the AutoMax Programming Executive

manual for more information.
Select the I/O Monitor function. For local I/O, enter the