Sysmac Studio EtherCAT Encoder

[Webbs]

I have a NJ301-1200 and I am wanting to set up an EtherCAT encoder on the machine to replace a incremental encoder.  I have only found absolute versions and purchased a Sick AFS60A single turn encoder (part Number 1059067).

I have the EDI file installed and setup the encoder and it moves through its 0-262,144 pulses and then goes back to zero as expected.  I want to set it up as a motion axis and have a linear count and to have it continue to increase with each rotation (like an incremental encoder does).  Is there anyway to set this up?

I am wanting to use a motion axis so i can adjust the current encoder position as the machine is running.

[viman]

I'm thinking of creating a variable to hold the encoder pulses and feed it directly the encoder value. That way it can go as far as big your variable is.

However, in the days of CP1 you had to use instant update functions (I can't recall the exact name), cause otherwise the PLC cycle isn't fast enough for an encoder. I have no idea about this in the new Omron PLCs though.

[Webbs]

Thanks viman,

I have thought about something like that, using a counter for each rotation and adding on the current encoder count to that but that could get messy and as you say there could be an issue with speed depending on the final PLC selection as a NX1P2 has a 2ms cycle time.

I will see if anyone else has any ideas otherwise i will go back to the incremental encoder and an encoder slice. 

[viman]

Which of these encoder cards you plan to get?

http://www.ia.omron.com/products/family/3190/

As an ethercat slave, they have a parameter called 'Max count setting' which lets you rise it up to 4294967295 (32bits).

[Webbs]

We currently use several NX-EC0222, one as a motion axis (encoder on a press) and others i just do the maths with the encoder count to convert it to mm.  For my new project to replace the Trajexia unit i was hoping to use the EtherCAT encoders but may have to use the current SEW TTL output encoders and use 4 NX-EC0142 cards.

[eulno]

Is there a reason why you choose a singleturn encoder. With multiturn encoders it will be easier to use the motion axis and no programming to do. 

[Webbs]

Hi eulno,

I looked at a multi turn encoder but running at a reasonable resolution it would count for about an hour of running and then reset back to zero.  The machine can run for several hours without stopping so there would be an issue when the encoders returned to zero.  There are 4 chains the product moves along each with pushers at different spacing  (process requirement).  The encoders are used to measure the current position (and speed) of each chain and an offset can be adjusted to align the pushers to transfer the product between chains.  The chains are driven by AC motors and  VSDs. Having the encoders position resetting its count to zero at different times while the line is running would cause adjustments to go out. 

I could look at having some maths set up to try and deal with this but would be easier to have a continuous count that only reset when the line stopped like we do now.

 

 

[Michael Walsh]

Using the Sick Encoder, what happens if you specify that it is an incremental encoder in linear mode?

[Webbs]

Hi Michael,

I have tried all 4 combinations of these all delivering the same result.  I spent some time with the Omron engineer yesterday trying a few different things including gearing with a virtual encoder/servo etc without success.  I have left the encoder with him and he is going to have a look at options.

I have also looked an an IO Link incremental encoder but i can't set it up as a motion axis - any ideas on is as an option?

 

[Webbs]

The Omron engineer had the unit for a week and wasn't able to make it do anything other than reset its count after each rotation.

I have written some math to eliminate the need for the motion axis.  I will look to extend that to keep track each time the encoder goes back to zero and just keep track of encoder turns.