Peculiar problem with rio modules

hi guys,
I am facing a peculiar problem with a flex input card that does not communicate with plc.The inputs go high in the module but is not read by the plc.
I am using 1794- asb & communication protocol is RIO.Its a full rack of 8 modules & only a single module does not reflect its inputs in the plc.

PLS HELP!!.. i am stuck !!

When I zoom in on Google maps I still cant see the Plc model, or what the modules are that are plugged in to the 8 slots or how any of them are wired

Either you need to give us more written data or some photo of what you have

https://maps.google.com/maps?q=+kol...72&hnear=Kolkata,+West+Bengal,+India&t=h&z=12

i have a 1794 asb ( adaptor module) followed by two analog modules(IE8), 4 input modules(IB 16), & 2 output modules(ob16) .All are mounted on 1794 TB3.

It could be a faulty 1794-IB16 module, 1794-TB3 wiring terminal fault (check the bus slide connector's pins) or the 1794-ASB module itself.
The bus fault might be located "upstream" from the faulty module so it will be pretty tedious troubleshooting.
I would first unplug all the modules and verify the bus connectors integrity; try replacing the IB16 module.
If these won't do it, replace the ASB adapter.
In case none of the above suggestions are successful, you will probably have to replace all the TB3 sockets, at least the ones between the ASB adapter and the troublesome input module TB3, including.

rejoe.koshy said:

hi guys,
I am facing a peculiar problem with a flex input card that does not communicate with plc.The inputs go high in the module but is not read by the plc.
I am using 1794- asb & communication protocol is RIO.Its a full rack of 8 modules & only a single module does not reflect its inputs in the plc.

PLS HELP!!.. i am stuck !!

Click to expand...

Is this a new install or has been working?

If always working:

Input module could be bad, or has a bent pin . You cannot remove these cards under power, so I would power down, swap the two input modules,turn back on and if the problem follows then its the card. If problem does not follow then is the TB base.

Ha-ha! I never thought to try and read missing information using Google Maps! That is good as any for many of the questions we get.

In a serious vein, I have had the ASB module stop reading a remote rack when the power supply was lost to the remote PLC. It required restoring the power AND a reset of the ASB module to restore the communications.

I have replaced asb module, the input module & tb 3 as well but the problem continues. what else can be done?
I have also noticed that when i remove a module under power up situation the asb displays a local fault, but when I recycle the power with module removed the asb module shows a healthy state.how can it show a healthy state when one of its modules are removed.??

If the replacement of the IB16 module and the 1794-ASB adapter returned the same results, perhaps it is time to replace sections of the 1794 bus; start with the first 1794-TB3 next to the communications adapter working your way towards the faulty input module socket.
Verify the functionality of the Remote rack after every TB3 replacement; you might get lucky and not have to replace all the wiring terminals.