PLC5/40B Interface to Ethernet Modbus TCP/IP

[newpageboba 7]

I have an application that requires a Modbus TCP/IP interface from a PLC5/40B. Our application has a PLC5/40 with DH+ to a 1756-DH/RIO via backplane to a 1756-ENBT for ethernet. The Application server needs a ethernet Modbus TCP/IP interface. I talked to Prosoft and they recommended a 5201-DFNT-MNET ( EtherNet/IP to Modbus TCP/IP Communication Module). I found out this will only work with a PLC that has a ethernet module. This module will not work this way unless the ethernet interface is in the PLC5or side card. Now, I am sending the module back (with a 20% restocking fee). Next, after talking to Prosoft, I am trying a 5201-MNET-DFCM (Modbus TCP/IP to DF1 Master Slave Communication Module). I am having problems. getting the cabling and RS232 settings correct for the connections from this module to a 1771-KE module. I have called Prosoft support twice, once I left a message and they did not return the call, second time they put me on hold for 15 minutes and then I got disconnected. This is weird, because I have never had problems with their tech support before. Looking at their web site, I found another module that I believe will be the best solution so far. MVI71-MNET (Modbus TCP/IP Communications Module) this module resides in the PLC5 chassis and connects directly to ethernet providing Modbus TCP/IP. The PLC5 talks to the module via block transfers. I have used a similar module, a MVI71-MCM (Modbus Master/Slave Communications Module), with excellent results In review, I am looking for a way to interface a PLC5/40B to Ethernet Modbus TCP/IP and I was looking for opinions and experience. What does the forum have to say????

[Ken Roach 194]

I would definitely recommend the MVI71-MNET. The MVI-series modules are Prosoft's "new platform", though they have about four years under their belts. They are based on a long-avalability x386 system-on-chip platform, so they should be able to build and sell them nearly indefinitely. The "Multi-Vendor Interface" has the same basic operating code and architecture and they package it into several different Allen-Bradley interface forms: 1794 FLEX, 1771 PLC-5, 1746 SLC-500, and 1756 ControlLogix. I like the widespread use of the same platform because it means that when I learn how to implement the Prosoft card in a PLC-5, all I have to re-learn on a ControlLogix is the difference between tag arrays and block transfers on the controller side. Most of my municipal customers rely on either an MCM or MNET module to interface with their generic Modbus equipment. The diagnostic port on the MVI modules is a thing of beauty. While it does make me dizzy, it's very satisfying to watch the console port with Hyperterminal and watch all the Modbus protocol goodness zinging by.

[newpageboba 7]

Thanks Ken, Sorry it took so long to thank you but I though I set up this post to email me when someone responded. So, when I didn't have an email I decided to check the posting and look there was a reply. I like the hyperterminal interface also, It seems to have every piece of info that one would need to check on the interface. But the big thing is...I don't need to figure out how to make the correct cable. Prosoft need to give more real world examples! I just wish that Prosoft would have recommened the MVI first and saved me a lot of grief. Thanks again.

[Rick-435NBx 0]

Hi, I work for Real Time Automation. Take a look at this module. http://www.rtaautomation.com/modbustcp/tcpgateway/ 490MB Might be something you can use. Rick

[newpageboba 7]

From what I see .. this won't help me go from PLC5 DH+ to Modbus TCP/IP. I need to convert to Modbus TCP/IP from DF1. Thanks anyway

[Mickey 71]

Maybe something here will work for you. http://www.protocolconverter.com/