1394 Servo Drive RIO Start Program

I have a 1394 Servo Controller setup with RIO. All the RIO communications are working except for the program start. From what I read in the manual, word 1-bit 4 is the start program bit and whenever the drive sees this bit it will start the program. Like I said, all the other control bits work. Is there a setting that I am overlooking or something? Right now I am having to leave a computer at the machine with GML Commander running and use it to start the servo program. The only time the servo program is stopped is when the safety circuit drops out(operator or maintenace needs to enter the machine.) But everytime, it has to be restarted from the GML software. I have checked the plc program to ensure the start bit is being made and everything looks OK there. Any ideas?
Thanks.

Did this work before?

Has anything changed?

Is the RIO comms healthy when you request the program to start?

Does the PLC hold the RUN bit true until it sees the program running bit in the input word?

It has ran before. Whe I got called to help with the machine the program had been wiped out of the servo controller. I found the latest revision of the program and downloaded it. The machine is now running and everything is working except for the start program bit. The PLC is holding the run bit true, but the program in the 1394 will not start except from the GML commander.

It may not help but for your information. In GML Commander, goto Configure/Control Options and check what was selected. You may need to check some options more and download program again.

I tried to reply last night from home but my Green Acres internet wouldn't send it...

Make sure the stop program bit isn't on during the same scan as the start program bit. I had one machine which would occasionally refuse to start the program even though it was done just like the example in the book. I ended up putting a delay between turning off the Stop Program bit and turning on the Run Program bit.

Check under Controller Options to see if Run on Power up is selected. This should not affect the ability of the PLC to start the program, but it might help you keep them running until you get to the root cause.

Does the e-stop/lock out remove power from the controller?

It is not uncommon for a system to start up with a fault condition, even a new fault condition after years of trouble free service. It is not uncommon for the fault handler to incorrectly deal with a fault. There are so many different ways to do things, and there are a couple of faults that are difficult to detect and program for.

Print blocks are your friend. I have had to add print blocks (to the terminal window port b IIRC) to many a diagram so I could trace what was going on at runtime. If you do this, just be careful not to put them inside fast running loops or you'll quickly overwhelm the serial port!

Now that I am at work, I'll search the knowledgebase at ab.com and see if there are other causes.

Paul

Do you have techconnect? Is the scanner a PLC-5?

I found AID 25768 to be interesting:

RIO comms appear to work one way only. (The PLC5 can read bits, but the 1394 doesn't respond to bits sent by the PLC-5).

The fix is to go to processor status, rack status S:27 and see if the bits are 00001000 change the 1 to a zero.