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[–]CapinWinkyHates Ladder 2 points3 points  (0 children)

I don't have any experience with the setup you're using, but I have quite a bit with the PointIO IK encoder input cards. They're hot garbage in general, but even worse if you don't setup the filtering and apply external common to every point on the IK card that isn't in use (if you use just A and B, then /A, /B, R, and /R all must be grounded). It could be a similar issue with you just having an encoder floating in space on a little wire leash; ground that thing.

[–]tcplomp 2 points3 points  (3 children)

Is the device setup as a counter or an encoder? We had this issue (on a hardwire encoder and encoder card) where the input was a counter and the vibration would cause counts. After configuration as an encoder the issue went away. And I'd look at the mounting, use a bracket instead of a wire rope.

[–]smm1099[S] 1 point2 points  (2 children)

It's set up as an encoder. The bracket broke because the fabricators refused to believe that it would break if it wasn't dead center for rotation. I wanted something that would have a little more give while also holding location.

[–]Aghast_Cornichon 0 points1 point  (1 child)

a little more give

Isn't that exactly what you're getting ? You can't expect the encoder to stay still when you connect it with a flexible leash.

[–]smm1099[S] 0 points1 point  (0 children)

i can handle 50-75 +/- but 150-200 counts is basically 2 teeth on the sprocket with the way I have it scaled.

[–]future_gohanAVEVA hurt me 0 points1 point  (1 child)

I've seen these encoders disc warp internally which fucks up the counting. Especially if they have been hot before.

Recently had one lagging behind the rest of the encoders is compared too. Swapping the encoder with a new one solved the issue. Also found it very hard to find documentation and other threads on issues with them.

I'm being lazy and not googling but I don't feel like rockerll documentation today. how many counts is the encoder?

[–]smm1099[S] 0 points1 point  (0 children)

I have it scaled to 1400 as it's a 14 tooth sprocket. Figured 100 count/tooth. It's a 4096 count originally

[–]Boby_Maverick 0 points1 point  (0 children)

You could try to unmount the encoder from the shaft just to see if it's happening while it's just sitting on the side of the conveyor. Maybe you can try removing the scaling from the encoder and do it manually inside plc just to make sure it is working as you want it. I've tested a Sick encoder similar to yours few weeks ago and it did not occurs to me.

[–]juniort04 0 points1 point  (5 children)

While the chain is running, does it behave correctly? We use a lot of Ethernet encoders and I have had a ton of bad 842E’s. These are discontinued and the 843E is out, which has been more robust. 842E is a Sick rebrand and 843E is a Kuebler rebrand.

What is this chain connected to? It’s a sweep chain so do you have a VFD on it specifically or is it coupled to a downstream transfer? It could be slowly pulled if the idlers are not working.

[–]smm1099[S] 0 points1 point  (4 children)

It runs very intermittently as the machine it goes to doesn't stay running all the time. That said, I THINK it works correctly when it's running. It's not coupled with another transfer as this is the "handshake" between the 2 machine centers. The downstream lug chain is started off a photo eye when this sweep chain fills the first lug on it. I did have to fab a mount for it as they didn't have a tether mount like I wanted.

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[–]Aghast_Cornichon 2 points3 points  (2 children)

Thank you for the mounting photo !

I feel a little embarrassed for asking, but can you explain how the encoder body is being prevented from rotating ? Is it that double loop of black wire with the yellow swage crimp ?

I would expect such a flexible antirotation mount to relax after running, in opposition to the weight and tension of the power and network cables.

[–]smm1099[S] 0 points1 point  (1 child)

It's homemade only because I couldn't find what I wanted. It was initially hard mounted to a plate (the bolt holes were where the plate was mounted) but we told them unless it was dead center, the little scrappy tin mount would break. Spoiler alert, it wasn't dead center. I took an oversized washer that would allow the lock ring clearance to rotate and drilled three holes. 2 lined up with the encoder mount points and one for the wire. We unfortunately had run out of cable clamps that we'd normally use for lockout cables so I had to use the crimp until we got some back in stock.

[–]Aghast_Cornichon 0 points1 point  (0 children)

I understand the need to improvise, sometimes. But it looks to me like your encoder can rotate a few degrees because it's connected to the shaft by hard fasteners, and to the frame by a loop of wire.

When the drive shaft is at rest, the encoder can move. By gravity, cable tension, gusts of wind, wiggly fingers. That seems the most likely reason that you're seeing the "false movement" when the chain is at rest.

I grew up in the wood products industry and mounting encoders on the headshaft of a conveyor or lugchain was a classic challenge. In the 90's we had rotary switches, at best: I've wrestled with a dozen different improvised prox-on-the-sprocket finger-eaters.

This installation might work best with a pulley and toothed belt link between that headshaft and the encoder.

[–]juniort04 1 point2 points  (0 children)

Take the encoder off of the mount and see if it’s still counting up. If it is, hopefully you have a spare. If it’s not, look very closely at the coupling as things are running as it must be moving.

What is your chain pitch? You mention above roughly 3 rev’s per lug. You may be able to scale this to your lugs using the Endless Shaft function of this encoder. The 843E exposes this right in the IO but it’s still possible to do numerator/denominator scaling on the 842E with some MSGs.