Removing analog I/O from PLC-5

Good day all. I'm in the process of removing old I/O from my PLC-5 as it is no longer used. For example: I would like to remove "FIC_1601 Mass Flow Setpt HF Line 1 LT_GEN_3". PLC-5 sends SP to the mass flow controller (MFC)using analog output module and address N14:401, and then the MFC sends the flow rate (PV) back to the PLC-5 analog input module using address N12:231. Doing a find all I see that these addresses are not being used by my project, however, the BTR and BTW are still active. What I would like to know is, if I physically remove the wiring for this particular analog I/O, will the system still function properly even though the BTR will no longer have data for this address? Thank you.

The RSLogix 5 project you have posted is password protected.
"password" doesn't work...could you post the functional one?
Theoretically, if any BTW/BTR is not successful in transferring the data it was configured to write/read, they will latch the .er (Error) bit, never set the .dn (Done) bit and that's about it.
Unless your ladder logic examines the functionality of the BTW/BTR and then "makes decisions" based on the state of the block transfer (or the lack of data it originally transferred) you should be able to unwire any module without any consequences.

dmargineau said:

The RSLogix 5 project you have posted is password protected.

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Sorry. Password is 5161. Thank you.

What I am unclear on is whether you want to remove a single analog point or remove the entire module.

The PLC/5 does not care or even know what cards are in its chassis. Each slot has one permanent 16 bit input word and one permanent 16 bit output word in the IO image table, and that word is present whether a card is present or not. Logix5 contains a rack configuration tool but that is for the programmers convenience. You can leave it blank if you wish. Analog cards require a block transfer to transfer more data and are configured in the ladder program. No special configuration is required as you would do on other platforms such as the SLC or CLX.

If you are removing the entire card I suggest that you place AFI at the front of the rungs of the BTW and BTR instructions for the obsolete module. Make sure you get both the configuration write block at first scan and subsequent read for the analog inputs and writes for the analog outputs. If you wish to remove the module from the chassis then you may do so without doing anything further (except power down the system before removing the modules). If you leave it there it will have no effect on your system except to consume a tiny bit of power.

If you are only removing a single point then you don't need to do anything further, however you should make sure that 0 is in the relevant output word of the output block N14:401 for the single point output. Rockwell does suggest that you short unused analog input terminals together to keep the input from floating, though its not necessary. Do not short unused output terminals.

I took a look at your application file and it looks like some BTW/BTR .dn status bits are being used to trigger other Block Transfer instructions.
Prior to AFI-ing any BTW/BTR rungs, delete any corresponding .dn XIC/XIOs present within your application.

dmargineau said:

I took a look at your application file and it looks like some BTW/BTR .dn status bits are being used to trigger other Block Transfer instructions.
Prior to AFI-ing any BTW/BTR rungs, delete any corresponding .dn XIC/XIOs present within your application.

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How do I identify the "corresponding .dn I/O's? I couldn't find any addresses that were used in the program that corresponded with them. Thank you.

Within the RSLogix 5 application file Data Files folder, pick the BT9 one and choose Usage; an X within the corresponding bit column indicates that the respective Block Transfer status bit is being examined within the application.

dmargineau said:

Within the RSLogix 5 application file Data Files folder, pick the BT9 one and choose Usage; an X within the corresponding bit column indicates that the respective Block Transfer status bit is being examined within the application.

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Ok, this I know. I just didn't understand what you were talking about, now I do. Im working with a system that is functioning. Is it possible to eliminate the BTR&W for one address, or am I best off to just leave the BT's alone? I disconnected the field wiring and the system seems fine with it. I just didn't want an unexpected "bump" in the road. Thank you.

It shouldn't be a major issue if everything seems to be okay without the field wiring connected.
However if the module is not going to be used anymore, during some "idle time", you should delete (or at least AFI) the BT logic related to it since it will return resources to the CPU and improve troubleshooting and/or eventual further development.