PLC5 RIO Flex IO OE4 communication

EngDave

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Feb 2018
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Ohio
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I've been searching the forums for hours and I've found many things to try but just haven't found the right answer yet. I have a running PLC 5 that has several remote racks off RIO. Rack 3 has a 16 channel DI card, a 16 channel DO card, and a 4 channel analog output card (OE4).

My question is: On rack 3 I can address the DIs as if they were connected directly to the PLC using I:30/0-17, the DOs are using O:31/0-17. How do I address the 4 channel analog card? Can I write directly to it? I tried with no luck. I read that I have to use a BTW. If that's the case then what should the R/G/M be? Would the rack be 3 or 003? Then I'm confused from there. Group 2? Module 2? I have yet to find a good manual that specifically explains what those mean. I don't know that I can attach the program itself but I can take screen shots of whatever is needed. Again from researching I read that I should look at the switches and S:2/11-S:2/12 are set to 1 Slot.


Any help would be great. Thanks.

channel properties.PNG
 
You will definitely have to use BTW to write to the analog outputs and BTR to read the analog inputs. I believe that the r/g/m will be 3/0/s where "s" is the slot number of the card in the remote rack. I am rusty on this stuff and don't have manuals handy, so I might be mistaken on the group and slot numbering.

The size of the block transfers will have to be correct for the module, otherwise it will fail even if you pick hte right r/g/m values.
 
The addressing you describe is consistent with "1-slot" addressing, where each module in the FLEX assembly takes up one "Group", which is equal to one "Slot".

In 1-slot mode, the "Module" number is always 0.

The 1794-OE4 will be addressed by your BTW instruction as Rack 3, Group 2, Module 0.

The 1794-OE4 has some differences in functionality between Series A and Series B with regard to the "multiplex bits" in the command data. Which Series do you have ?
 
OkiePC's recollection is incorrect, which is a rarity !.

In 1-slot addressing, the "Group" number is what you would generally think of as a "Slot", or a physical module position.

FLEX I/O supports up to 8 modules per adapter, and is virtually always used in 1-slot addressing mode. A full set of 8 modules would be a "Full Rack".

When the 1794-ASB adapter powers up, it will see three modules attached, and automatically round up to 4 modules, making itself a "1/2 Rack".

Code:
Input Module:   Rack 3, Group 0, Module 0
Output Module:  Rack 3, Group 1, Module 0
Analog Module:  Rack 3, Group 2, Module 0
Unused:         Rack 3, Group 3, Moudle 0

RSLogix 5 has a fairly handy wizard for RIO configuration that will insert BTR and BTW instructions into your logic. You can designate the BT control file elements, and the Integer (N) files that contain the source and destination data for each of the block transfers.
 
Thanks guys. Thank you for the explanation Ken. I've been looking for information on that. I did try that initially but I think I found my mistake. After the yes/no option for continuous I would hit enter which would then attempt to open the setup screen at the bottom of the btw command. And I would get the "No Modules Exist in the IO Configuration for this R/G/M." and would assume I messed those up. So again thanks I got it working now. I did have to put in a 15 on word 5 for the multiplex bits. (I think that's what they are called. I thought I also read somewhere where they are enable bits.) So I set those high, plus the setup bits for 0-10v and now I have a nice 0-10 volt signal. Thanks for all your help!

btw.PNG
 

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