Devicenet Messaging

[Tinker 0]

Hello all, I have red eyes from trying to find how to make this work. I want to pass a message from Node 1 on a Devicenet system to Node 2. This is just to start as I have 7 Nodes to pass information around to. For now I am trying to get the firs one passed. I just want to send a bit to let Node 2 to let it know that a downstream conveyor has stopped running and to shut down. Sounds simple but it has got me pulling out my hair. I have read information here as well as AB manuals and searched the internet and I am sure that I am missing something simple. Any Ideas?

[Ken Roach 194]

First question is what sort of device those nodes are, and whether they have messaging abilities. Are you using the Bulletin 1799 Zone Control I/O modules ? Those have a very specific node-to-node messaging protocol.

[Tinker 0]

Sorry I am using SLC 503 on all nodes. A Bulletin 1747-SDN that is on Node 1. No on the 1799

[Ken Roach 194]

Sounds like a good application for Slave Mode on the 1747-SDN's. The 1747-SDN can be a DeviceNet Master to a bunch of I/O devices, while simultaneously being a DeviceNet Slave to another 1747-SDN. The "Slave Connection" maps into the I/O table of the slave 1747-SDN just like any other I/O connection. Double-click on the 1747-SDN, go to the Module tab, and click the "Slave Mode" button to enable Slave Mode on each module.

[Tinker 0]

OK Ken thanks for the help. Once again my overworked mind failed me.. I am trying to work with a DH485 system (see Atch). However the Master/Slave idea sure did get my mind running with some ideas. There is only one 1747-SDN on my network and it is on Node 1. Any way how about the DH485 route, any ideas anyone?

[Tinker 0]

Did I say something wrong? I can reword the question if I need to, sometimes I do not state things just right.

[Ken Roach 194]

In your first post you said you were trying to get data between nodes on a DeviceNet, but I see now that you only mentioned that the 1747-SDN is on Node 1. So, are you trying to pass data between SLC's on a DH485 network, or are you trying to pass data between controllers that are on the DeviceNet network attached to the 1747-SDN scanner ? The slave-mode method only works with DeviceNet. On DH485 you'll have to program MSG instructions. Tell us more about the system and your functional requirements.

[rpraveenkum 5]

You should use NetAIC+ in place of AIC

[Tinker 0]

Thanks for the information Ken and rpraveenkum. What I want to do is DH485 useing program MSG instructions. I whish to talk from one CPU500 to another. There are 7 SLC 5/03 PLC's on the network at this time. I have been studying MSG instructions but fail to understand how to send a bit to tell one 503 that a conveyor on another 503 has stoped running and I want it to shut down the conveyors that it controls. Clear as Mud?

[rpraveenkum 5]

Many node in Dh485 causes problem like network overload & so on Better to have 5/03 with net eni or 5/05 in ethernet

[Tinker 0]

net eni? I an not familiar with that one.

[gravitar 3]

http://www.ab.com/programmablecontrol/plc/...ix1000/eni.html It is essentially a small DF1 to Ethernet/IP gateway.

[BobLfoot 301]

Tinker - with this many nodes DO NOT USE MSG WRITE or you will be very disappointed in the lag time. You have 7 SLC 5/03's lets call them A,B,C,D,E,F & G. What type oF communication do you need? Option 1 - A to B and back, B to C and back, C to D and back, D to E and back, E to F and back, F to G and back Option 2 - A as master to slaves B,C,D,E,F & G and answers back. Option 3 - A,B,C,D,E,F & G to A,B,C,D,E,F & G If you can specify I can suggest a structure.

[Tinker 0]

Option 3 - A,B,C,D,E,F & G to A,B,C,D,E,F & G This would allow me to go from any one to any other one. The system I am working with was installed so communications could take place but no one has ever attempted to do so until now. I have just been working for this company for a few months and I an just now trying to piece together what was done and why.

[BobLfoot 301]

This will take a while to explain and the addresses I use can be changed to fit your situation. In PLC A place MSG Read PLC B start = N22:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC F start = N26:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC B place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC F start = N26:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC C place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC B start = N22:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC F start = N26:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC D place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC B start = N22:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC F start = N26:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC E place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC B start = N22:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC F start = N26:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC F place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC B start = N22:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC G start = N27:0 Length 64 In PLC G place MSG Read PLC A start = N21:0 Length 64 MSG Read PLC B start = N22:0 Length 64 MSG Read PLC C start = N23:0 Length 64 MSG Read PLC D start = N24:0 Length 64 MSG Read PLC E start = N25:0 Length 64 MSG Read PLC F start = N26:0 Length 64 This will give you 64 registers of shared memory between all PLC's. You'll want to create an excel map to describe the tags.

[Tinker 0]

Well it is the weekend so I must work on things such as motor installation and fixing guide rails and the like so I will start on the first part of next week and get back to you when I am done. Thanks for the information BobLfoot

[BobLfoot 301]

Glad to Help the length of 64 is arbitrary, but is gauranteed to transfer in 1 packet. lerger exchanges may take two packets and thus two trys with more delays.

[paulengr 44]

I'm not all that familiar with DH485. Can you also use the global bits to pass information around like you can with DH+? In DH+, there is a block of 64 words that are passed around as part of the token. It forms a sort of shared memory. The offset into the block corresponding to the node number is a broadcast address for that node. Interestingly, if you have any unused node addresses, all the others are a free-for-all. Anyone can write to it and use it as broadcast memory. If such a puny amount of memory is acceptable, you get MSG'ing for free.

[Tinker 0]

Question: Should these just be true rungs to the MSG?