Help With Problems - Siemens SIMATIC NET OLM12M Description And Operating Manual

6ZB5530–3AB00–0BA0/01
8

Help with Problems

LED Display
System LED not lit
System LED lit red
CH1 LED not lit
CH1 LED lit
PROFIBUS nodes
nevertheless report bus
problems
CH2, CH3 LED not lit
CH2, CH3 LED lit
PROFIBUS nodes
nevertheless report bus
problems
If all the LEDs indicate correct operation and there are still communications problems (for example
acknowledgments missing, unexpected frames), check the monitoring times (for example the slot
time) on the PROFIBUS nodes.
For more detailed information, refer to the description of your PROFIBUS DTEs.
In large PROFIBUS networks with numerous modules and long cables, the delay caused by
network components and lines (transmission delay) must be taken into account when you set the
monitoring times.
To check this setting, you must calculate the transmission delay time (TTD):
The transmission delay time is the maximum time that elapses when transferring a frame on the
medium from the transmitter to the receiver.
Copyright Siemens AG 1997
Possible Cause of the Problem
- Power supply outage
- OLM12M defective
- Break on the receive FO cable to the partner module
on CH2 or CH3 (to localize the defective channel,
refer to 'CH2, CH3 LED not lit')
- Unused CH2 or CH3 is not set to the 'Inactive' mode
- Break on one or more wires of the RS485 LAN cable
- Wire A and B of the RS485 LAN cable have been
swapped over at the terminal block
- Connected PROFIBUS node is defective or not
transmitting
- PROFIBUS node is not connected or connected
PROFIBUS node is not activated
- Wire A and B of the RS485 LAN cable swapped
over at the terminal block
- Short circuit on the RS485 LAN cable
- Break on one of the two wires of the RS485 LAN
cable and wire A and B swapped over at the terminal
block
- No or incorrect termination
- Send and receive FO connectors swapped over
- Break on the receive FO cable to the partner module
- No partner module connected or connected partner
module is not activated
- Connected partner module is defective (not
transmitting)
- Channel is set to the 'Inactive' mode
- FO connector is loose (bad contact)
- FO cable to neighboring module too long
- Break on the receive FO cable and extraneous light
entering the system
27
SIMATIC NET OLM12M
Signaling
Contact
signals
signals
does not signal
does not signal
signals
does not signal