Incremental Encoder as Absolute?

[Paul Ked]

I have an incremental encoder with A B & 0 outputs. Putting these into X0, X1 & X2 and rotating clockwise I get 0-359 and resetting every revolution, great! What I'd like to do when the motor reverses is to count back down to zero and then revert back to 359 so I can display the angle of rotation on the HMI. I am using the FX3u, is there a command I can use to do this? If not, any suggestions as to how I go about this? Best Regards Paul Ked

[panic mode]

only 360ppr? anyway, i didn't work with that plc but the idea is to configure those inputs for quadrature encoder.

[sid]

You can use the A/B Phase counter with reset input as your zero point signal of encoder. I have not woked with FX3u but after checking manual i found C252 can be used for your purpose.

[Paul Ked]

I'm only using a cheap encoder for this application (360ppp) as I only need to monitor the direction of rotation and the speed is only 6rpm. I am using C252 for this, but it is this counter that counts backwards once it gets to zero and is moving anti-clockwise. What I need to do is to somehow shift the data so that when I get -1 through to -359 is negate the number and invert it ie when C252 = -1 then D*** = 359 through to when C252 = -359 then D*** = 1. I always considered myself ok with maths but this has got me stumped! Best Regards Paul Ked

[Colin Carpenter]

Have you tried moving the value of C252 to a register then adding 360 to it?

[Paul Ked]

[Colin Carpenter]

You're welcome, Paul. I've been stuck in my own "DO" Loop more times than I care to remember