ControlLogix Bridge Module

Working on starting a system with AB ControlLogix Bridge Module - The card indicates "No Tx" and A#00 with the MOD/NET flashing red.

The card is in a logix 5561 all ethernet system.

Any ideas to resolve??

Look on PDF page 48

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/dnet-in001_-en-p.pdf

Thanks for the PDF of the module.....Any ideas on searching the for the fault? Probably tell by my question we are not PLC savy. We know its probaly not necessary to replace the communication module based on the literature.

That error code suggests a 1756-DNB DeviceNet bridge that is not connected to a usable DeviceNet network.

Can you tell us more about what network cables and devices are connected to the module ?

The "A#00" just means that the 1756-DNB has been assigned Node 00 on the DeviceNet. That's very common for a Scanner.

The "No Tx" message indicates that the 1756-DNB can't transmit on the network. Because DeviceNet is a serial bus system, any device that is transmitting should be able to hear its own transmissions to check for signal quality, and "No Tx" means that the DNB cannot. That suggests that the blue or white wires are disconnected or damaged, or that the network termination is improper.

With 24V DC turned off to the network (the red and black wires) you should be able to measure about 60 ohms between blue and white wires. 120 ohms means there's only one termination resistor; lower than 60 means there's more than two.

If there was some other data corruption or signal problem you would probably see a "Bus Off" error 91. Absence of received data would give you a "No Rx" error code.