Trouble Shooting
If you're having problems with the module, the status LEDs provide indications of what might be the cause.
Avoiding typical errors
Checking the PROFIBUS wiring
A PROFIBUS cable (or a cable segment when using repeaters) can be checked with a few simple resistance measurements. The cable should meanwhile be removed from all stations:
|
Measuring points |
typical resistance |
|---|---|
|
Resistance between A and B at the start of the lead |
approx. 110 Ohm |
|
Resistance between A and B at the end of the lead |
approx. 110 Ohm |
|
Resistance between A at the start and A at the end of the lead |
approx. 0 Ohm |
|
Resistance between B at the start and B at the end of the lead |
approx. 0 Ohm |
|
Resistance between screen at the start and screen at the end of the lead |
approx. 0 Ohm |
If these measurements are successful, the cable is okay. If, in spite of this, bus malfunctions still occur, this is usually a result of EMC interference. The installation notes from the PROFIBUS User Organization should then be consulted (www.profibus.com).
Configuration sequence
When configuring an IP-Link with analog and digital extension boxes, always enter all the analog boxes first, in the sequence in which they are connected to the IP-Link. Then enter the digital boxes in the sequence in which they are connected to the IP-Link. Inputs and outputs are then mapped.
Configuration errors with the IL230x-B3xx
Fieldbus boxes that possess less than eight bits of process data in the input or output areas are rounded up to eight bits, and thus occupy eight bits in the relevant region. Note that this applies, for instance, to the IL230x-B3xx boxes, which have four inputs and four outputs.
IP-Link error
If the IP-Link error LED is lit, or if it flashes irregularly, it means that transmitted telegrams are faulty, if indeed they exist at all. The modules may indeed be amplifying each telegram, but cannot correct an error once it has occurred. The error must therefore be traced back from the last module to the first error-free module. The source of the error lies in the connection between this module and the following module.
The error is nearly always due to IP-Link cables with too much attenuation. This can, for instance, arise during cable assembly. A visual check is the simplest test. When held up to a source of light (but one that is not excessively bright), the surface of the relevant connector should be uniformly lit. Both sides should be checked.
In case of doubt, the connector must be assembled again. Ensure, when carrying out this work, that the optical fiber is not ground back too far.
Take care during the assembly that the correct length of insulation is stripped.
The finished cable can be most easily tested by connecting it between the Coupler Box and Extension Box. If the cable has been connected correctly, there will not be any faulty telegrams.