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Module
Malfunction
Communications
Signal Problems
4-2
Troubleshooting
When power is applied to the PPX:505-2571, it first performs a Power On
Self Test (POST) to determine if all module components are operating
properly. This test takes only a few seconds. When successfully completed,
the ACTIVE indicator on the module will be illuminated (on steady). If a
problem is detected with the communications section for one of the ports,
the ACTIVE indicator will begin blinking at a fast (2 Hz) rate. If a problem
is detected with the controller interface section, the ACTIVE indicator will
begin blinking at a slow (1/2 Hz) rate. For all other problems this indicator
will be extinguished.
NOTE: If the PPX:505-2571 ACTIVE indicator is illuminated (on steady)
after the module is powered up, the module is most likely OK. If you have a
communication problem, it is probably the result of factors other than a
module failure, such as a cabling error.
Although you must log the PPX:505-2571 into the controller as 2 WX inputs
and 6 WY outputs, these values are unused in this version of the
PPX:505-2571.
The most common sources for signal problems are bad cables and
improperly configured operator interface devices. The RCV and XMT
indicators can be a valuable aid in troubleshooting these errors.
If the RCV indicator for a port does not flash briefly when you attempt to
send data to the PPX:505-2571, no signal is being received by the module.
First, determine that the operator interface device is indeed sending data
(refer to the operating manual for the applicable device). If the operator
interface is sending data, then you most likely have a defective cable. The
cable may have broken wires or connectors or it may be improperly wired.
The best way to troubleshoot this is to substitute a known good cable. Refer
to the wiring diagram in Chapter 2 of this manual to check if the cable is
properly wired.
If the XMT indicator for a port flashes briefly, it indicates that a signal is
being sent from the PPX:505-2571 port. If the XMT indicator flashes but no
signal is received at the operator interface device, then there is most likely a
cable problem. Follow the procedure outlined above for checking cabling
problems.
SIMATIC 505-2571 Program Port Expander Manual
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