Ti 315 Plc

When I try to establish communication from the TISOFT2 software (on PC) to the TI 315 PLC I get the error message "checksum failure" and no online operation. How do I correct this problem ?

What operating system are you using and what cable do you have? The old Tisoft stuff was developed in the DOS days. I have used it on a 315, don't remember what operating system, though. I do remember it took about 3 minutes for the connection to establish. It was at a slow baud rate. The 315 was not designed to work with a computer, just a handheld. Does the 315 have a RS232 port or a verticle rectangle connector that requires a DCM-02 or 03 (Data Communication Module)? I think you may need a DCM and that may be hard to find.

I take it that the plc is no longer functioning?

Usually a "checksum failure" means that the program has gone belly up and/or there is something fatally wrong with the plc. Most often this is either that the battery has died (I am assuming that the 315 had battery backed memory, I've never used one) and power was lost to the plc causing the memory to corrupt, or the capacitors on the internal power supply have degraded to the point that the plc is running on too low of a voltage to support communications.

Most often it is the power supply. As far as I know there is not a readily available processor to directly replace the TI315. You might hunt around some of the remanufacturers to see if any of them have one laying around that works, but the best bet is just to replace is with something more modern, after all it is over 15 years old.

Icky812 and RRobbins are right on the mark about the 315 failure. If it is a battery failure the battery indicator in the CPU and DCU should be on. If you have a backup of the ladder program one possibilty is to go into the AUX functions of TISoft and attempt to clear memory first and redownload the program. If the 315 is functional the Aux functions should allow you to go online regardless of the corrupted program. There is still some of the 315 PLCs floating around being sold as used or reconditioned. If you want to go that way I would suggest checking the following:

http://www.plccenter.com/Search_New_copyV1.asp?OFFSET=35&VTI-GROUP=0&R1=1&T1=315

or

http://www.erdweb.com

Sometimes you can luck up with:

http://www.juneusa.com/

If you do decide to move to a more current system the 330 and 340 CPUs are still alive and well. While the hardware is different, modular vs. brick, most people have a very high success rate at transfering the program directly from a 315 to a 330 CPU. The 340 will yield the same results but also has a built in RS232 port so the DCU is not needed.

Hope this helps,
Andy