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View Full Version : AB Point IO, MDS iNET-II, and CLX


Mike6158
October 29th, 2008, 10:14 PM
Has anyone here used AB point IO over an MDS iNET Ethernet network. I've got the PLC configuration done and online. I've got some issues with the Ethernet radio network because the contractor didn't mount the antenna's high enough (RSSI in the -90 range) so for now I'm waiting on them to fix their problem before I can do my part. I was just wondering if anyone else had done this and if they had are there any gotchas that I need to be aware of?

The system consists of (6) AENBT's with (2)AI, (1)AO, (2) DI, and (1) DO. Each rack has it's own iNET radio. Distance to the access point is 2.8 miles. Flat terrain. Trees to about 25'. All antennae are under 15' AGL right now (hence the problem). The point IO is connected to a CLX L61 processor via ethernet (duh)

Fred_Loveless
October 30th, 2008, 10:20 AM
We have several customers using MDS modems with CTLX controllers. You have already seen the big gotcha. The rest are typical issues inherent in long range communicaitons. Don't overload the network and make sure that there is enought time between a response and the next request for data for the modem to switch from recieve back to transmit your communications server should have a mode to select for radio ethernet modems or it should have an option to set an inter request delay.

Mike6158
October 30th, 2008, 07:15 PM
We have several customers using MDS modems with CTLX controllers. You have already seen the big gotcha. The rest are typical issues inherent in long range communications. Don't overload the network and make sure that there is enough time between a response and the next request for data for the modem to switch from recieve back to transmit your communications server should have a mode to select for radio ethernet modems or it should have an option to set an inter request delay.

Fred- I'm not using the iNET-II's to communicate to the processor (as in HMI to processor or a SCADA application). I am using them as a Bridge between remote IO that AB calls Point IO and the CLX processor 2.8 miles away. There really isn't a way to scehedule requests over the ethernet network other than increasing the RPI in each AENT module associated with the CLX processor. It's a non-critical application but it needs to work. I'm hopeful that once we establish a decent comm path there will be no issues.

Ken Roach
October 30th, 2008, 07:32 PM
The truth is, Mike, I've had a lot of customers experience problems with this kind of system. The radio vendors seldom understand what kind of traffic is running on the network and even the best radios behave differently with large amounts of multicast data at cyclic rates.

Is the Logix controller connected to the Access Point ? That would be my guess as the usual architecture.

The outgoing data from the controller to the POINT adapters will be UDP unicast, with a normal IP address target.

The outgoing data from the POINT adapters to the controller will be UDP multicast. As long as the radios properly propagate UDP port 2222 out the wireless side to the Access Point, you should get smooth I/O connection communication.

I very strongly recommend from the beginning writing good diagnostic code that periodically examines the Module object with an GSV instruction to make sure the connections are remaining logically active and to give you some tools and background if users start to claim that the wireless link isn't working correctly.

MDS was a Rockwell Automation "Encompass Partner" until they were acquired by GE, so they might still have some application experience or technotes for you about specific tweaks or tricks with their radios.