DH+/RIO issue

[sweetjohnny]

I have series of plc's linked together using DH+, that go to a 1756-DHRIO/E card. My problem is i cannot see any of these plc's in RSWho, it will populate the list, and intermittently find one of the node's and appear to be communicating, then drop right back out. I have walked my entire line, and made sure there are no breaks in the DH+ wire, and all my connections are tight and the resistor at the end is intact and good. odd thing is that the DH+ light is on and green on all the processors, and all my PV's (pv 600's) are all working. I have a seperate computer that is using wonderware as an HMI for all the plc's and it can see and make adjustments to them, but i cannot see them in RSWho, they are all X'ed out. Any ideas?

 

[Paullys50]

Is the 1756-DHRIO card new? Or has it been in service and now you are having problems?

If new, do you have the dip switches setup for the proper speed and node address?

If old, has anything changed in the network?

 

[sweetjohnny]

The card has been in service for almost two years now. No nothing has changed on the network...

 

[ShaRK]

I've seen this before, where I caould see everything on the network except everything below the 1756-DHRIO/E card.

Have any changes been made to RSLinx, like a revision update? Different laptop, new patch? Sounds like the network is happy.

 

[JesperMP]

It sounds as if you have quite many nodes on the same network.
How many exactly of each type ?

Maybe your network has always been running at the limit, and then just recently adding a few tags somewhere has just pushed it over the limit.
Can you remove one of the Panelviews for example and see if it improves things ?

You can check the diagnostics counters of all the nodes, and see if one sticks out. If there are many retries it could be that node or its partner that has a problem.

the resistor at the end is intact and good

The "ends" ! Both ends must have termination resistors.

 

[sweetjohnny]

No changes in linx, no new patch, same old laptop (new laptop on the way though).

No new tags, i will check the counters.

Sorry to make the resistor comment singular, yes they are both good and intact. on both ends.

 

[ShaRK]

Are you connecting over an Ethernet connection via the ControlLogix bridge, or through DH+ on one of the nodes?

 

[sweetjohnny]

replaced card, and all is well. Thanks for all the help.