User manual

Pulse Catch Input
Mode 50
UP Counters
Installation and
Safety Guidelines
7–10
Pulse Catch Input
DL205 High Speed Counter
Interface Manual, 2nd Ed, Rev. A
Troubleshooting
The following information may provide some assistance in handling any problems
which may be encountered when setting up the D2–CTRINT module, should they
occur. Experience has shown that most problems occur because of improper
configuration. Always re-check configuration before anything else.
For verifying types of inputs (or outputs) which do not relate to the Pulse Catch Input,
see the Chapters in this manual covering the specific function. Listed below are
some things that could possibly go wrong with the high speed interrupt inputs:
1. No pulse catching appears to be taking place.
2. The status indicator LED is not lit for the input point where the pulse
catching is wired (i.e. points 00 and 01).
Defective Field Device - If a field device is suspected to be faulty, verify its proper
operation first. Examine the characteristics of the pulses being received with an
oscilloscope, test equipment type digital counter, or an inexpensive logic probe.
High Signal Indicator
Low Signal Indicator
Pulse Train Indicator
Normal/Pulse Train Switch
TTL/CMOS Switch
Typical Low Cost Logic Probe
Connect power leads to your recommended
power supply––not PLC power supply.
(Not available from AutomationDirect)
Touch probe to
counter input points.
Field device must be
wired so that pulses
are being sent.
Check the specifications for the field device. Make certain that the output signal
matches the specifications of the D2–CTRINT module.
Pulse Width – The pulse width may be too narrow. The positive transition must
remain HIGH for at least 0.1 ms in order for the module to detect its presence.
Wiring - Simple as this might seem, quite often poor wiring is the cause of many
problems. Be sure there is a complete electrical loop between the device and the
input module. Along with visual inspection, use a voltmeter to check the wiring.
Input Voltage - If the input device is sending a signal that is less than 12 volts, most
likely the counter will not function or function improperly. Replace the field device
with one which has the proper output level if necessary.
Improper Configuration - Verify that proper values have been used in the
configuration. If interfacing a DL230, point 00 is the only point available for pulse
catching.
Status Indicators – Make sure the PWR or BAT LED’s are not lit on the CPU. Be
sure that the status indicators are lit as the pulse signals are received at the proper
input point on the D2–CTRINT module. If an LED is not functioning, check the point
with a voltmeter to be sure that the I/O point is being energized. .