While there are some variances based on software, the communication loop is similar to the following:

Pass #1, the processor will communicate with I/O#1 first, then I/O#2, and if the machine has it I/O#3. Then it will communicate with the Output cards starting with #1, then #2, and if the machine has it #3. Then the processor communicates with the D/A board, and then if the machine has a water meter it will access the meter for an update through I/O#1.
This pass is repeated two more times.
On the 4th Pass, the loop is repeated and at the end of the previous loop the processor will communicate with the A/D board and then get the RPM data from I/O#1, if it has programable speeds for the cylinder. Because of the RPM data, I/O#1 must be a high speed board. If it is a regular speed board, it will come up I/O#1 failure. If the machine is a multimotor drive there is no way to program a variable speed, thus the first I/O card will be a standard I/O card and not a high speed I/O card.

Since the A/D board is only communicated with once every 4 passes, the serial link light will blink at 1/4 the rate of the other cards. If it is blinking at the same rate, check the addresses as it thinks it is something other than an A/D card.

With all boards removed, the display should show I/O#1 failure. After you put the first I/O in, the next error should be I/O#2. After I/O#2 is installed, the error should shift to I/O#3. This process should continue all the way through as you keep adding one board at a time.

If after installing the D/A board, it comes up I/O#1 failure again, then look at the address of the I/O boards to ensure that it is a high speed board for the #1 address location.

When in program menu configuration menu, the processor only communicates with the first I/O and the first Output card. You can remove all the other cards. If the serial link is not working, the problem has to be the processor card, the wiring, or one of these two cards.

CSH 04/18/13

Keywords
Processor Card
Peripheral Card
Microprocessor
I/O
Out
A/D
D/A
Input
Output
Digital
Analog