Remote I/O

bosox51879

Member
Join Date
Nov 2004
Location
Reading PA
Posts
1
I am new to Remote I/O so hopefully somebody can give me a hand...........I am familare with the fact that by where you scanner module is placed in your rack that will set up your rack 0-4, group 0-7, bits 0-16 I/O images...........I also am familar with setting my G File parameters as well to 1/4,1/2,3/4,Full.........

However how do you actually make communication occur through the Remote I/O network to operate devices.

Also how do your MO and M1 files work in brief.......

Thank you very much
 
If you are so familiar with these things, then what is the problem ?

But OK, each scanner that you insert in a SLC500 rack will provide 32 input words and 32 output words.
If the scanner is in the first slot after the CPU, then the i/o addresses will all have a ".1" in them to tell that they are from slot 1. Like I:1.0/0 for the first digital input address, and O:1.0/0 for the first output address.

You have to setup the scanner in the IO configuration in RSLogix. Under "adv. config" you will find the "edit G data" button.
By adding "racks" to the list of devices you match the real i/o on the RIO network.
What is confusing here is that "logical rack" is not directly related to a physical rack. A "logical rack" is 8 input words and 8 output words. If you need less than that for a device, you can assign a 1/2 rack or a 1/4 rack or 3/4 rack to save some of the precious RIO address space. Likewise, it is possible to assign more than one logical rack to a physical rack if you need more than 8+8 i/o words.
You must match the settings that you make in the G file, with the settings in the i/o racks. This is typically done with dipswitches in the RIO adapters in the remote racks.

All that these i/o addresses can reach are the digital i/o.
Specialty modules such as analog i/o must be accessed via block transfers. There are BTR and BTW instructions available for this purpose (*). AB have examples for the various analog modules on their knowledgebase. I recommend that you find the instructions that match your analog modules, and use these as a template.
The M0 and M1 files are used with the block transfers.
The M files access the scanner module directly, so lots of block transfers will increase your program cycle time.

*: If the firmware version of the CPU is recent enough.
 
Just to expand on Jesper's comment. To use BTW / BTR the processor must be series C.
However, there is a work around, but it's not easy.
You can read and write to the M files ( using MOV & COP instructions) and accomplish the same thing. I've always had a hard time determining exactly which piece of the M files went with what I/O device, because parts of the file are for status and other house keeping functions, so you have to calculate an offset.

When the C series came out, I jumped for joy. It's so much easier now you simply read and right via Block transfers to the desired rack/module. It's worth the money to upgrade the firmware rather than spin your wheels trying to figure out the M files. As mentioned earlier AB has many BTW/R articles in the knowledge base.

Here's a LINK to the knowledge base search page.
 
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