Rockwell Automation 57C421B Pulsetach Input Module/DCS 5000/AutoMax - Manual (Page 44)

5Ć2
Rotate the pulsetach in the forward direction. The
FORWARD LED on the module's faceplate should turn
on. Rotate the pulsetach in the reverse direction. The
REVERSE LED should turn on. If the LEDs do not turn on,
the module's pulse input circuitry is not working correctly.
If the pulsetach rotates in the wrong direction, the
pulsetach input wires must be switched. In a
singleĆended wiring configuration, swap the A and B
inputs. In a differential wiring configuration, swap the A
and not A inputs.
Remove power from the rack and the pulsetach.
Reconnect the coupling between the motor and the
pulsetach. Reapply power to the system.
Step 4. If external inputs are used, verify that the external input
circuitry is working correctly.
Toggle the external input device. Verify that the LED
associated with that particular bit (LATCH, COUNT STOP,
or CLEAR) is also toggling. If it is not, the external input
circuitry on the module is not working.
If the input triggers on the incorrect level (as specified in
register 6, bits 12, 13, or 14), it may indicate a problem
with switch bounce. Care must be taken to eliminate any
switch bounce before the input. If switch bounce persists,
a proximity switch or photoelectric sensor with hysteresis
is recommended.
Step 5. Verify that the module can be accessed.
Connect an IBMĆcompatible personal computer to the
system and load the Programming Executive software.
Refer to the AutoMax Programming Executive instruction
manual for more information.
Using the MONITOR I/O selection, monitor the external
input device and determine whether the bit is changing
state when toggled.
If you are able to read the input, the problem is in the
application task. Go to step 6. If the programming device
cannot read the inputs, the problem is in the hardware.
Go to step 8.
Step 6. Verify that the I/O definitions are correct.
For modules in a local rack, the slot number must agree
with the slot that the module is actually in. Verify that the
register and bit number are correct.
For modules in a remote rack, a master Remote I/O
module (M/N 57C416) must be located in the master rack
and connected via a coaxial cable to a slave Remote I/O
module located in the drop that contains the Pulsetach
Input module.
Verify that the master Remote I/O module is in the correct
slot. Next, verify that the drop number on the faceplate of
the slave Remote I/O module agrees with the drop
number being referenced in the task.
The slot number must agree with the slot that the module
is actually in. Verify that the register and bit number are
correct.