GE 90-30 Serial Comms

[patb63]

I have a question for concerning a GE 90-30 (350 CPU) and serial communications. I'm trying to connect to a PC through an IC693CMM311R communications coprocessor. I think I have one of the ports as an RS-232 and the other as an RS-485. How can I receive data from a PC and store it to make decisions in my program? I have 5 scanners sending info to the PC and it will tell the PLC to divert or pass a carton at each decision point. Any ideas? Thanks for the help

[Steve Bailey]

You will need an application running on the PC that can communicate using either SNP, CCM, or Modbus RTU protocol. The application on the Pc will be a master and the CMM311 port will be a slave. With that configuration, you will not need to add any ladder logic to the existing PLC program to handle the communication. It might be easier to have the scanners (barcode scanners?) send their data directly to the PLC. Can the scanner transmit its data using Modbus RTU? If not, you may need a PCM module instead of the CMM311. The problem I envision with your setup is how to synchronize the data from the scanner with a particular box. Maybe you've already dealt with that.

[patb63]

Yes, each message from the PC will have an identifier in the message to show which divert location it belongs to. The PC will be running a vB program to communicate with this company's Warehouse Management System. The PC will "look up" previously downloaded data to determine where the cartons should travel in the conveyor system. How complicated will it be to set up and use the protocols mentioned on the PC? Thanks again for the help.

[Steve Bailey]

Places like Kepware and Software Toolbox sell serial drivers that you should be able to integrate into your VB application.

[patb63]

Talked to GE Tech Support today. They said the only way to do straight serial communications was to use a IC693CPU352 or IC693CPU363 processor. The second port on them can be configured for "normal" RS-232 use. Thanks for the help. We have a new processor shipping to us tonight.

[RussB]

That "is" true, but doing what Steve suggests will be less programming and less money. Also, Did they say that it is the "best" way to do what you want? IMHO, an IC693CPU374 and an Ethernet connection to the PC using Modbus TCP/IP protocol would be the best solution. BTW, why would tech support recommend the CPU352, it has been obsolete for more than a year now. Edited July 25, 2006 by RussB

[patb63]

Money not really an issue...company we're working for is purchasing all the GE parts we use. They "recommended" those two processors only because they have serial ports. I'm really struggling trying to get this communication thing to work. All for a lousy four character message!!!!!!

[RussB]

Then, get an IC693CPU374 and a Kepware SRTP OPC driver, you should be finished in less than an hour.

[patb63]

I guess I still can't believe it is this difficult to read 4 characters over a serial port...I still can't get this stupid thing to work...even with the 363 CPU.

[Steve Bailey]

Chapter 9 of GFK-0582 describes what you need to do in order to set up the port on the CPU363 to receive character strings and the COMREQ instructions that need to be executed to process the data. Are you following that? Post your logic and I'll try to help debug it.

[patb63]

Not sure how to post the code unless I just send you a copy of the program. Then again, with this Proficy Machine Edition, not even sure I can do that easily. I've tried following Chapter 9 (as much as my feeble brain will allow). I'm using a leading edge output (one shot) energized from photoeyes at my scanners to do the Data Move instructions that I thought would tell the PLC to read the port for data. (Not real sure how to make it keep looking until data is there.) I've been trying to use Hyperterminal to simulate my server PC's communications, but I get zilch from the port, or at least in the registers I try to put the data..

[Steve Bailey]

Do you have a utility that can create pdf files? If so, you can print the pertinent rungs to a pdf file and post them in the downloads area of this site. Otherwise, make a backup of your project and post that. If you (or your employer) are unfortable with posting the program for all the world to see, email me through this site. I'll respond with an email address that you can use to send the backup file to me.

[patb63]

Got it to work somewhat today through Hyperterminal with the file I downloaded just now. It seems to work okay most of the time, but sometimes won't flush the buffer. Don't be too critical of the code...I haven't used GE software for twenty five years. Thanks for any help you can give. BTW, when I called GE Tech Support today for some help, I was told I would have to wait until Monday because the plant wouldn't be down until then. Guess what hardware and software I don't want to use anymore.

[Steve Bailey]

The pdf file you posted has only one page. The right hand side of the logic where the coil instructions should be didn't fit on the page. Only the first two IN nodes of the Block Move instructions in rung 3 are on the page. If there are rungs 4 or higher, they are not included in the file.

[patb63]

Sorry about that...this job has me addle-brained. Looks like I might have gotten the communications to work finally.....we'll see for sure tomorrow. I'll make a good post of the code when I get back home from here.