RIO Addressing

I am in the middle of a project which needs me to use remote IO which I have never setup before.I have read the user pdf files for the scanner and the adaptor modules and think I have got it sussed.Just thought Id check before diving in.The scanner card is in slot 9 of my rack ,I have two remote 4 slot racks each containing a 1746 IB16, a 1746OW8 and 1746 NI4. I decided to use 1/2 slot addressing as image space isnt an issue and the client wants the code to be a simple as possible so i dont need to do any block transfers.Anyway I think the addressing should be as follows
Addressing Rack 1
Input card: - I: 9.0/00 – I: 9.0/15
Output card: O: 9.2/0 – O: 9.2/7
Analogue Card: - I: 9.4 channel 0, I: 9.5 channel 1, I: 9.6 channel 2, I: 9.7 channel 3,
Addressing Rack 2
Input card: - I: 9.8/00 – I: 9.8/15
Output card: O: 9.10/0 – O: 9.10/7
Analogue Card: - I: 9.12 channel 0, I: 9.13 channel 1, I: 9.14 channel 2, I: 9.15 channel 3,
Is this correct?

I'm assuming your using a SLC CPU since all your cards are from the 1746 series. If this is true, I do not believe your data is correct.


The only way to handle remote analog I/O that I'm aware of is to either read and write to the M file of the scanner, or if you have a series C processor use the block transfer function. I find the block transfer to be the easiest to setup.

Here is a knowledgebase example using a NI8 and reading the M file:
http://domino.automation.rockwell.c...3BBF08875C97053685256AFB0067EA84?OpenDocument

Here's a link on BTR/W: http://domino.automation.rockwell.c...FC07C5A35898838085256AFB0069FA95?OpenDocument


Ken

It looks as though it should work fine. Make sure you set you 1747-ASB to discrete IO.
The only thing I am not sure about is the fact that you are using a 4 slot rack and you are using 2 words from the next slot which does not exist. We have used a similar arrangment but with a larger rack, and we needed to leave the slot after the 1746-NI4 (4 point analog input) empty because of the extra 2 words that it required.

I prefer to use single slot addressing and block transfers for the Analog cards because 1/2 slot addressing is a little harder to understand. (Speaking for myself that is).
i.e. If the first slot is I:9.0/0 - I:9.0/15 most people would expect the next card to be O:9.1/0 - O:9.1/15, not O:9.2/0 to O:9.2/15.
Also I don't like the idea of having slots which I must leave empty, and I don't like the idea of having all that wasted Scanner space.

I must agree that using discrete I/O with Analog card is much easier than block transfers. Although using the new BTR and BTW instructions with the newer processors sure beats the old code that you had to use.

Kim

From the way I understood the pdf files I read I didnt think that it mattered that there wasnt physically another slot available after the analogue card .I was just going to set each remote rack up as a full logical rack so I asume the analogue card will just use up the next two input words.Maybe I am wrong?
Or maybe I should use block transfers.At least then Ill know how to set them up in the future and it shoulndnt be much of an issue with the client as long as i comment it up properly.
The hardware hasnt arrived yet anyway so I guess I decide on it over the weekend.

I would try your original configuration, I think it will work fine.
If it doesn't you can either use a larger rack or use Block Transfers.

Kim

2 4 slot racks.
1/2-slot addressing. 4 channel analog inputs. Direct addressing without block transfers.
Last slot in rack not used.

There will be no problems with this addressing scheme.