1756-HSC issues

The Setup:
We have 2 counter cards in the 10th and 11th slot of a chassis. On each card are two independent pickups that monitor flow turbines. The cards are set up to counter mode and the Storage Mode is set to "Store and Reset, and Start Mode". The rollover, Preset and Scaler values are all set to 0. We are using 2 outputs on each card that stop the flow for each turbine and only have one “on” value for each and everything else is set to 0. Output 0 is tied to counter 0 and Output 1 is tied to counter 1. Once we start a cycle at one channel, we monitor the flow and once the corresponding counter reaches the “on” value we stop the flow (through the card’s output) and reset the counts via the gate input.

The Problem:
When we start counter 0 and then after a short delay, start counter 1, we run into an issue of the gate 0 resetting both counter 0 and counter 1 values. Counter 0’s flow has stopped and counter 1 hasn’t so this causes counter 1’s volume to be much higher then the required amount. This is only happening with the card in slot 10 and not the card in slot 11.

Steps taken:
1. I have swapped the cards and still got the same issue with the 10th slot. (not a card issue).

2. I removed the gate wiring from channel 1 at the card and forced on the PLC output which drives the gate for channel 0 and saw it reset both counters. I then replaced the gate wiring for channel 1 and removed the gate wiring for channel 0 at the card and then forced on the PLC output for gate 1 and it only reset channel 1. (Not PLC code).

3. I swapped the wiring arms (RTB’s) and still had the same issues with the 10th slot. (not a wiring issue).

4. I moved the card in slot 10 to slot 12 and still had the same issue. (not a chassis problem)

I have a message command in the logic to write the configuration to the card on first scan and I have a feeling this is where the problem might lie. I have put an AFI in the rung after start up and the problem still persisted.

In the message command I set 124 bytes in the source length, just like the manual says to, but one thing the manual doesn’t tell you is what each byte represents. The manual also says that each counter has an independent reset gate.

My questions are:
Where can I find what each byte does in the message command?
Has this happened to anyone else and if so what did you do to resolve it?

Without seeing the program, it seems likely that somewhere, for that counter, you are physically writing to one of the modules output words, perhaps even unintentionally, or issuing a software reset.

There is no need to message the module, unless you need to perform an online, program controlled re-configuration. Everything that can be set up for most purposes can be set up in the module configuration dialogs.

rdrast,

No, No, and yes. <---answers to your suggestions. But I have tried to prevent the software reset and even the messaging command and I still have the same problem. One thing I don't get is that the second card in the chassis is working, no problem.

The PLC program was a conversion from RSLogix 5 to 5000, so i carried all the programming over and just had to change a couple rungs/bits/words/etc. and I just found out that the original programmer had never even heard of a PLC before he tackled this project! That said you can imagian how crazy this code is. The progam used to write a message to the card every cycle (~5-10 seconds) and I found that it was not needed, so I changed it to only write when we need to change the Output On values. Remember, the code is the same for card 2 and works on that one, but not on the first card!

What I really want to get is a detailed, Byte for Byte, description of what the message command does. Does anyone know where I can find that?

Just to let everyone know, I have solved the issue. I reflashed the cards to version 2.1. I had to do this twice in order for this to take place. I also removed the cards from the chassis after flashing. This was a tough one as I had already flahed the cards and the problem didn't go away and the problem didn't follow the card, it stayed at the problme slot.

Anyways, if you have a gate issue, try and reflashing the card.