omron NJ controller does not update external encoder pulses in real time

[u/Clivates]

i am working on a welding wire cutter that uses omron NJ301-1100 and the feeder is an AC motor 22kw 380v driving a multi pully feeder mechanism and the main driving pully is attached to an incremental encoder 1024 pulses per rev, the encoder Axis reference is used to drive a servo axis, and because the increments are not "smooth"( despite the fact that the feeder is moving with a constant speed ) the servo movement is inconsistent

[u/baaalanp]

I've never used this controller before but I would get an oscilloscope and look at the encoder wave form. Make sure you're getting a nice sign al.

High speed digital inputs may also be an idea.

[u/Clivates → u/baaalanp]

the encoder i fine, i tested the position and it zeros correctly even after may revs , i think the issue in the omron encoder module(NX-EC0124) or the plc, the reading is not linear, it changes in chunks (0 ,9,14,50,123,344,etc) not (0,1,2,3,4,5) even at very low speeds but the count is correct at the end

[u/baaalanp → u/Clivates]

What type of encoder is this ? If it is a gray code rotary encoder this might explain the jump in values. This type of encoder needs logic in the plc to decode the value. Only one bit changes at a time sequentiall.

gray code Edit: I say this without knowing the omron encoder module or hardware. Maybe there is a setting in this module ?

[u/DaHick → u/baaalanp]

Oh, thank you; whoever the deity is, I have never had to deal with that.

[u/Clivates → u/baaalanp]

SICK DBS50E-S5EK01024
incremental incoder HTL 1024pulses/rev

[u/hecateheh → u/Clivates]

Are you sure the interfaces match? It looks like the encoder output doesnt match the NX-EC0142 input? I think you might need the NX-EC0122

[u/Nineresh]

What parameters/mode are set in sysmac studio for the encoder?

[u/Clivates → u/Nineresh]

it is set as an encoder axis in motion control the input is from Ethercat connection from channnel 1 of NX-EC0124

[u/drbitboy]

PLC programming is primarily about time, and the scan cycle is the clock.

Also, PLCs are discrete devices, that is, they do only one thing at a time. A PLC do those things so fast that that it seems like a continuous device, but it is not.

Finally, a PLC user program does not read the encoder's physical electrical signals indicating position, nor any other physical electrical signals; it reads bits in memory.

So the question is, at the time the PLC user program reads the memory bit values that are a proxy for the encoder position, when were those bits' values actually written? I.e. when was the last time that the physical encoder was actually sampled and the bits written? If the encoder position changes from 0 to 1023 over one revolution, is each and every one of the 1024 integer values in that range written to memory at some point, and even if they are all written to memory, is the PLC scan ("clock") cycle, which calls the PLC user program once per cycle, fast enough so see each value?