Field device is not detected – Rockwell Automation 1788-EN2PAR EtherNet/IP and ControlNet to PROFIBUS PA Linking Device User Manual User Manual
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Rockwell Automation Publication 1788-UM058B-EN-P - September 2014
Chapter 4
Diagnostics
Field Device is Not Detected
Use these diagnostic checks to help you identify and fix the problem when a field
device is not detected.
Table 4 - Field Device is Not Detected Diagnostic Checks
Symptom
Checks
The linking device AOP scan reports NO DEVICES FOUND when
linking devices are connected.
Are the PA node addresses set on the field devices?
If you are using the soft address setting, add only one field device at a time and set the node address before
adding the next field device. If you do not set the node address before adding the next field device, the field
devices default to a node address of 126.
Verify that the PA node address does not conflict with existing field devices on the network.
Verify that the PA node address is
less than or equal to the max scan
address in the linking device AOP.
Verify that the field device has power.
If a display is present, verify that the display is illuminated.
If no display is present, use a voltmeter to check the voltage across the PA terminal in the field device (verify
correct polarity). See the field device manual to see minimum input voltage. The longer the cable and the bigger
the load (number of field devices and junction boxes), the bigger the voltage drop across the cable.
See
for a description of cable length guidelines.
Verify that the PROFIBUS PA network cable is not in a noisy environment. Keep away from power cables, drives,
and other sources of noise.
Verify that the cable shield is connected at the linking device and at the junction box, and not at the field device.
Verify that the shield is not touching the instrument casing or gland.
Tape off the cable end.
Verify that the network is sufficiently terminated (not over or under terminated).
Typically, a terminator is placed at the start and end of the PROFIBUS PA network. In some network
architectures, the linking device can terminate the start of the PROFIBUS PA network.
See
Termination Guidelines on page 21
for termination guidelines and network architectures.
Verify that the network topology
setting in AOP matches the physical
network topology.
See
for
configuring the topology in AOP and
network architectures.