Modbus Question

[PLCGuy]

I am trying to connect a H2-ECOM100 to a Denso robot controller. The card is suppose to be able to handle modbus. The contoller's inputs start at address 512. I set up the ecom card with the peer-to-peer. All entries seem to be correct. I am just doing the WR to the controller first. I have LD K701, LD K2, LDA O40620, WX V1000. I tried numerous values for the WX such as GY1000, X1000, GX1000. I used SP136 and SP137 tied to counters and watch as both counters count. Obviously I do not want to see the SP137 count errors. The Denso of course caters to AB's EthernetIP protocol, but the card claims it does modbus. There is a $1300 unit that will go between the AD ECOM100 and controller to make it work. I really do not want to do that. It just seems I do not have the right value for WX. I took 512 and put it in the Excel Spread Sheel AD has. It Showed 512 converts to GY1000 or V1000, depending if the start address is bits or words. In any case, neither worked. Do I rally need to but a expensive card to do conversion from modbus to EthernetIP? I found out AB, Mitsubishi PLC's hook up fine to Denso. WHEN will there be a common protocol for all? Why isn't there a DEVICENET for the DL205? Presently the Devicenet card goes where the CPU goes. The DL06 is not that way. It is too late to change out the DL260.

[Controls Guy]

Do you have a link to the manual for the robot?  Where it says it will do Modbus?  That might give us some more insight.

[PLCGuy]

That is just it, it does not. It only says it will do EtherNetIP (AB). The card manufacture is saying the card will do modbus. It is a third party doing the ethernet card for Denso. They are out of Germany. You think that is where the problem is? After reading your question, I believe that is why the other customer ended up getting that bridge device. So is it even though the card will do modbus, that doesn't mean the controller is capable of doing modbus over TCP/IP?

[Controls Guy]

Well, if it's a simple Ethernet adapter, similar to what's in a PC, it's meaningless for the manufacturer to say it will do Modbus.  Any Ethernet card will do Modbus, because the card isn't doing it anyway.  It's more like their card doesn't NOT do Modbus.  There has to be an application layer in software or firmware that understands Modbus framing and can assemble and parse the requests and responses.  Now it could be that this card is more sophisticated than a PC Ethernet card, but the device into which it was plugged would probably still have to be Modbus aware.

SST used to have a cool product OEM's could integrate that came in flavors for all the various industrial fieldbuses and presented a uniform memory interface to the OEM's product.  So the OEM could build one design and offer 10 different fieldbuses by ordering and popping in a different module.  That type design would be a way in which the robot might be compatible with busses it doesn't know it is, but I doubt that's what you're dealing with.

[PLCGuy]

I ordered a bridge from HMS Anybus. It will connect AD Modbus as master to the Denso controller as slave, Ethernet/IP. You seem to be correct as to say the controller does not do modbus. How stupid is that. Come on people AB isn't the only thing out there. It seems Denso got involved in the market when AB was out there and now customers want other plc's and denso has to do something, so it seems the bridge is the way to go for now.