another way to slice the pie ...
Greetings Amy,
after the further update on your actual hardware from our phone call, I’ve gone just a little bit further with the DIP switch settings for the 1747-ASB modules ...
suppose that we set the 1747-SN/B scanner up like this:
and suppose that we keep the hardware set up the way you described over the phone ... double-check this figure and make sure that I understood you correctly ...
if the figure is correct, then you could set the DIP switches as shown above ... this would give you convenient access to the empty slots - just in case you ever need them in the future... with this set up, the Block Transfer rungs for the two 1746-NI4 modules would be the same as I attached in a previous post ... and the “N11” addresses of the analog input channels would remain the same as in that previous post ...
this is probably the best way to go, based on what I know (or think that I know) about your project ...
but ...
just suppose that you could move each of the 1746-IA8 modules as shown below ... and suppose that you leave the three extra slots at the ends of each chassis empty ...
with that arrangement and with the DIP switch settings shown, things might get a lot easier for you ... specifically, you could make use of the scheme mentioned on page 3-11 of
this manual ...
this means that you wouldn’t need any block transfer rungs at all ... specifically, the analog addresses for the 1746-NI4 in slot “L” would simply land right on the processor’s input table like this:
Channel 0 = I:9.16
Channel 1 = I:9.17
Channel 2 = I:9.18
Channel 3 = I:9.19
and the analog addresses for the 1746-NI4 in slot “S” would land on the input table like this:
Channel 0 = I:9.24
Channel 1 = I:9.25
Channel 2 = I:9.26
Channel 3 = I:9.27
this would be a lot easier for other technicians to work with too ...
the downside of this “no block transfer” arrangement would be that any future use of the “extra” slots at the end of each remote chassis would require some major modifications (addressing changes, etc.) to your program ... on the other hand, if you don’t think that you’ll ever need those slots, you might consider swapping the two 7-slot chassis that you have for smaller 4-slot types ... you could use the larger ones on a future project ... just something to think about ...
and incidentally, the addresses of the 1746-IA8 module in slot “N” would be I:9.20/0 through 1:9.20/7 ... and the addresses of the 1746-IA8 module in slot “U” would be I:9.28/0 through 1:9.28/7 ...
anyway ... keep us posted on how things are working out ...
PS edit ... I just read your e-mail information but I haven't had time to go over it ... it would be a good idea to post everything about your system on the open forum ... there are many people here who can help ... just check with your boss first about any proprietary issues ...