Plc to plc communications via radio

[chrisbramall 1]

Has anybody used a KE card before. I've got a project on the go which should work but hitting configuration problems. I am basically networking two SLC5/04  PLC's which have no available cable route. What I have used is SLC5/04< -> AIC <-> KE <-> Radio --- Radio <-> KE <-> AIC <-> SLC 5/04 Also connected to the AIC unit on each end is a panelview 600 the panelview 600's and the AIC are using the DH485 protocol. The KE card is configured to convert from DH485 to DF1 for the radio on both sides. The problem is when i've got the system together I can see one side but not the other. If I connect direct to the radio I can see the PLC & HMI on the other system. Any ideas !!!

[Guest Ken Roach]

Chris, This network bridge arrangement isn't the usual function of a 1747-KE module, and I don't think it will work quite the way you expect.   You will not be able to hook up RSLinx to one side of the DH485 and "browse" through to the other system. DF1 protocol doesn't include a "remote Link ID" or "remote gateway" field when used with DH-485.   It can with DH+ (a system of 1785-KE Series B would do this exactly, but at much higher cost), but not with DH-485.   Remote Data Highway (I, II, Plus and 485) are a dizzying topic and I'm not an expert despite having worked here for five years ! So, when a message goes from DH485 to the 1747-KE, it comes out the DF1 side with the same destination address as when it came in.   This means you can communicate from Network "A" to only one node on Network "B", and that node has to have the same DH485 node number as the KE module on Network "A". Probably you went with the straightforward method of numbering DH485 nodes: Network A               Network B           Node 1 SLC-5/04 Ch.0    Node 1 SLC-5/04 Ch.0 Node 2 PanelView 600    Node 2 PanelView 600 Node 3 1747-KE          Node 3 1747-KE So, if Node 1 sends a message to Node 3 on Network A, the 1747-KE will pass it through on DF1 with the destination node 3.  When it arrives at the other side, it'll get transmitted to Node 3... the KE itself, instead of where you really wanted to send it, Node 1. So how do we get around this ?  "The Address Mirror Trick" Network A               Network B           Node 1 SLC-5/04 Ch.0    Node 1 1747-KE Node 2 1747-KE          Node 2 SLC-5/04 Ch.0 Node 3 PanelView 600    Node 3 PanelView 600 Now, a message on Network A sent to Node 2 will be answered by the SLC-5/04 on Network B. A message on Network B sent to Node 1 will be answered by the SLC-5/04 on Network A. This should let you go online with either SLC-5/04 from either network, as well as allowing the PanelViews to read from both SLC's.   The feature you won't have is the ability to download and upload to the PanelView 600's on both networks. Let us know how it turns out. Regards, Ken Roach A-B Seattle kiroach@ra.rockwell.com

[chrisbramall 1]

Thanks alot. I could not find that in any of the manuals and that has really saved my bacon. At last a forum where those taking part know what they are talking about. Cheers, Chris

[chrisbramall 1]

Well It's D Day on monday. As the system will be powered up in anger for the first time. If it does not work then the sh1t will really hit the fan! and before you tell me off for using foul language the PLC is involved in transfer of sludges on a sewerage works to the digesters, so it is appropriate. I'll try and post back over the coming fortnight on my progress, trials and tribulations just incase someone is interested. If not I suppose you'll all tell me to stop waffling.

[chrisbramall 1]

Further to an email today from Ken asking if the advice he had given was successful. unfortuanately due to problems on site the second half on the communications link is not up and running yet. We should be powering up on Friday so i'll let you know.

[chrisbramall 1]

Well guys all smiles here. Got the second PLC up and running today. Reconfigured the KE cards and it works. The radios are running at 19200 baud and transfer around 100 words of data per second. the main problems I had after sorting the KE cards was configuring the MSG function correctly. I am reading 50 words and writing 50 words. Originally they could both transmit at once onto the network and I found that it tended to swamp the DH485 networks leading to errors on the panelviews. After reseting them into a sequence so that only one transmits at a time I could even undertake on line programming on one PLC whilst connected to the AIC unit at the other PLC. Still needs a bit of fine tuning as additional kit comes on line but that will be over then next two months. Thanks to all those that helped and all who were interested enough to read