CPM1a via modem

[PeterRichter 0]

Hi I am trying to set up remote acces to a Omron CPM1a PLC (with CPM1a CIF01 rs232 adapter) and just don't seem to be able to get it. I'm using a sixnet VT-1 modem. I have exhausted the help from sixnet and the local omron dealer. I want to access it from my computer at home. I dont need the remote modem to dial out. I am using Syswin as the connection software. I have used the sixnet general PLC setting template and changed the protocol to the default in the PLC (9600 baud 7 bit even parity 2 stop bits). I was originally trying to use the built in modem in my PC and laptop, and could get some sort of communications between the modems and then a fault message saying "no carrier". I read that these type of modems often don't work in this situation (especially 11 bit), so i tried and old external modem (acer 56 surf) and seem to have gotten one step further. The message I get now is "no response from PLC". I think I've got the right settings in the remote modem but I'm not sure about setting up the modem and coms port on the local computer. The lead I am connecting between the modem and the PLC has pin2 - pin 3, pin 3 to pin2 sig gnd to sig gnd. I have pins 4 and 5( rts, cts) bridged on the PLC end and pins 7 and 8 (rts cts) and 6 and 4 (dsr, dtr)bridged on the modem end. I am not sure if pin 1(dcs) should also be bridged in with these as well. I have flow control turned off on the PLC modem. Should I have flow control turned off on the local end? WHat about DTR control? Am I better of setting everything to the standard 8 bit, no parity, 1 stop bit? Has anyone actually done this set up or can anyone offer any advice. The sixnet application notes only cover two particular types of Omron PLC - not the CPM1a. I've been at it for weeks. The omron dealer says that they offer an "omron" modem - but it is just an office modem that they have put the settings in. I would much rather use a proper industrial modem. Thanks in advance to anyone that can help Peter Richter Richter Process Control Redcliffe, Qld Australia richter process control@ optusnet.com.au

[Jay Anthony 118]

Suggest you read this article from the home page of MrPLC.com Using Modem with Omron Host Link From your description, I suspect SG problems. SG is Pin 9(Not Pin 7) on all Omron 9 Pin serial ports. The article gives the pinout for the PLC to Modem Cable and instructions on how to setup Syswin.

[PeterRichter 0]

Thanks for the response Jay. I am already using pin 9 as the signal ground on the PLC end. It is connected to pin 5 which is gnd on the modem (9 pin plug) Peter

[PeterRichter 0]

In the Syswin communications setup there is a place to put an initialisation string - Do I need to put something in there? Peter

[PeterRichter 0]

Sorry that Init string I was talking about was in the setup for the sixnet modem - "User defined AT string" should I be putting something there? or is that just for dialling out? Peter

[PdL 71]

All modems I used had the connecting cable from modem <> PLC connect TD/RD straight, so pin 2 <> 2 and pin 3 <> 3, not 2 <> 3 and 3<> 2 like you described.

[gtsuport 61]

Peter, I posted to this same thread on PLCs.net (checked that site first this morning). The other document I was thinking about is the link Jay gave you. The sixnet setup is in the link I posted in the other forum. Good Luck! Sixnet Modem Tech Note @ omron.com Edited 13 Oct 2005 by Jay Anthony

[PeterRichter 0]

Thanks I've read that application note before, but I'll have another go at it and just pretend that my CPM1a is the same as the one in the note. I noticed this time that there are two different places to select the flow control. I was just setting both of them to none. Maybe I should be using flow control on the first window to actually talk between the PC and the modem as it is being set up. (maybe the setting weren't actually going into the modem properly) Does anyone know if - even if i use no flow control on the PLC end, whether I should still use hardware flow controll on the local (PC) end. Is that side of the communications completelty irrelevant to what happens down the other end? I've been using a cable which only connects the tx and rx and gnd wires between the PLC and modem - but I'll give it a go with the flow control wires connected as well even though flow control is turned off. My programming cable that connects from my PC to the PLC uses only the two signal wires. Ive got a PSTN emulator on the way. That should make experimentation a bit easier. ( I was actually trampling my own children, racing backwards and forwards to use next door's phone line!) I'll let you all know what I eventually come up with - Maybe I'll even publish my own technical note to give to Omron and Sixnet In the meantime - Any suggestions are welcome Peter

[gtsuport 61]

Omron 9 Pin/Pin designations: RX(pin 3), TX(pin 2) and SG(pin 9), plus CTS(pin 5) and RTS(pin 4) usually must be shorted together. Typically, without the pin 4 to pin 5 short, communications won't work. Modem setup may be an issue. It has been a long time since I set one of these up. From memory, I think DSR (Data Set Ready) and DTR (Data Terminal Ready) may cause communication problems if not properly configured. You may want to check that setup on the PLC modem end. Hope this helps..

[Guest anonymous]

Hey Guys, Howsabout CX-Modem? If you've registered your product, it's a free download from... http://softwaredownload.europe.omron.com/E.../fhome?openform The tool provides monitoring for PC to Local modem, Local to Remote modem, Remote modem to PLC, which helps identify where the connection is being lost. Also available are factory or user defined settings (AT commands), which can be downloaded directly to both Local and Remote modems, enabling relatively painless modem communications to the PLC. (The help also contains the required pin-out diagrams for the cables etc). Peter, I know you're using Syswin, so it may be a problem registering unless you have CX-Programmer or some other up to date Omron software, but others following this thread may find this info of use. Regards anonymous

[PeterRichter 0]

Well, I finally got it. You're all going to think I'm a @#$% idiot. I had been leaving the sheild wire for the PLC - modem cable off at one end. This is because, a lot of sheilding applications I have come across don't need the sheild on at both ends - and a lot require that you only connect one end. I fact even most of the diagrams I saw of PLC - modem cables only have it on one end. I have even read horror stories of people burning things out by having sheild connected at both ends when there is a potential difference between the two earth references. Anyhow, I connected the sheilds together and hit "connect" again, not expecting anything to happen, and up she fired! That was with some pretty way off coms settings too. It seems that some of those settings arent that critical. Thankyou all that offered help Regards Peter