AB 1746-HS module & Offsets - PLCS.net

ammauric · June 11th, 2018, 12:30 AM

Hello everyone,

I have a project I've been working on involving a single 1746-HS (IMC 110) and a SLC 5/02 - the original 1746-HS had fried without any backup and the customer wants me to attempt reprogramming the replacement based on what I've interpreted from the PLC program before they go to more drastic measures of replacing the equipment.

The system I'm working with is rather simplistic. It's a roller (rotary axis) which feeds steel into a press a specific distance, based on a user input.

I've had success so far in programming within the MML, setting up manual functions, and triggering events from the PLC, but there is an offset that comes from the operator that I haven't been able to get working. The PLC outputs it to word 3 (MSW) and the existing logic toggles between speed override (set to 0) and position offset to signify the change, since I believe the changing of states is what triggers the write process.

However, I'm not sure how to access this register within the MML. I thought it would be shared with $OFFSET, but I can't seem to get that function to work at all. I've tried using it similarly to $SPEED but no matter what my offset remains 0 and the servo moves the same amount.

Thanks for any help anyone might be able to provide. I've already spent a couple of days on this project, and a lot of time outside of it combing through the programming manual... I'm beginning to reach my wits end.

ammauric · June 11th, 2018, 12:31 PM

A quick update to this, I found out while working this morning that the offset command doesn't work on the MOVE BY move command for some reason, even though its descriptor says it works on all move commands. I've circumvented this by using MOVE TO CURPOS, and when using a static offset it's working exactly as expected.

However, as soon as I load an offset into memory, it won't offset at all as if it were 0.

ammauric · June 22nd, 2018, 11:30 PM

I had solved this awhile ago, but should anyone stumble upon this thread in the future with a similar problem. What I had found was a discrepancy in the programming manual. It lists a table of bits for mapping the Speed Override, Offset Position & Preset Position but has two of the columns for the output bits swapped so I had my PLC program commanding the wrong types of overrides or invalid ones.

The table is listed in two separate areas, and I had only been referencing the latter incorrect one.

June 11th, 2018, 12:30 AM	#1
ammauric Member Join Date: May 2013 Location: Michigan Posts: 10	AB 1746-HS module & Offsets Hello everyone, I have a project I've been working on involving a single 1746-HS (IMC 110) and a SLC 5/02 - the original 1746-HS had fried without any backup and the customer wants me to attempt reprogramming the replacement based on what I've interpreted from the PLC program before they go to more drastic measures of replacing the equipment. The system I'm working with is rather simplistic. It's a roller (rotary axis) which feeds steel into a press a specific distance, based on a user input. I've had success so far in programming within the MML, setting up manual functions, and triggering events from the PLC, but there is an offset that comes from the operator that I haven't been able to get working. The PLC outputs it to word 3 (MSW) and the existing logic toggles between speed override (set to 0) and position offset to signify the change, since I believe the changing of states is what triggers the write process. However, I'm not sure how to access this register within the MML. I thought it would be shared with $OFFSET, but I can't seem to get that function to work at all. I've tried using it similarly to $SPEED but no matter what my offset remains 0 and the servo moves the same amount. Thanks for any help anyone might be able to provide. I've already spent a couple of days on this project, and a lot of time outside of it combing through the programming manual... I'm beginning to reach my wits end.

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June 11th, 2018, 12:31 PM	#2
ammauric Member Join Date: May 2013 Location: Michigan Posts: 10	A quick update to this, I found out while working this morning that the offset command doesn't work on the MOVE BY move command for some reason, even though its descriptor says it works on all move commands. I've circumvented this by using MOVE TO CURPOS, and when using a static offset it's working exactly as expected. However, as soon as I load an offset into memory, it won't offset at all as if it were 0.

June 22nd, 2018, 11:30 PM	#3
ammauric Member Join Date: May 2013 Location: Michigan Posts: 10	I had solved this awhile ago, but should anyone stumble upon this thread in the future with a similar problem. What I had found was a discrepancy in the programming manual. It lists a table of bits for mapping the Speed Override, Offset Position & Preset Position but has two of the columns for the output bits swapped so I had my PLC program commanding the wrong types of overrides or invalid ones. The table is listed in two separate areas, and I had only been referencing the latter incorrect one.

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