Siemens 505-2571 - Manual (Page 26)

Troubleshooting 4-4 SIMATIC 505-2571 Program Port Expander Manual
Table 4-1 Troubleshooting Matrix
Symptom Probable Cause Corrective Action
Active Indicator light not on. 1. No Power to module
2. Defective module 1. Ensure 5V power is supplied to
the rack
2. Cycle power. If ACTIVE indicator
does not remain on, replace the
module.
Active Indicator Flashing Defective module Cycle power. If ACTIVE indicator
does not remain on, replace the
module.
RCV indicator does not flash
when attempting to send data
from an operator interface device. Defective module. Most likely a
defective cable. Possibly an
operator interface device failure or
configuration error. Check communications cable
wiring. Replace with a known good
cable and retry. Replace operator
interface device with one known to
be good.
XMT light does not flash within
two seconds of receiving a signal
on the port (RCV indicator
flashes). 1. Baud rate mismatch
2. Hardware handshaking error.
3. Protocol error. 1. Correct baud rate settings.
2. Enable operator interface
hardware handshaking or set
PPX:505-2571 hardware handshake
to DISABLED.
Intermittent Communications
Problem 1. Communications “noise”.
2. Ground loop problem 1. Reduce baud rate; replace or
re-route cabling.
2. Ensure proper grounding; install
isolation equipment.