what servo motion instruction to use? MAM, MAG, MAJ, something else?

[unsaint32]

We have a servo motor for a tubing coiling (rotating) arm. I'm using RSLGX5000 (V19.01.00), CTLGX 5000 (1756-L61), and Kinetix 6500. The coiling arm has no certain destination position. It should stop rotating when the encoder reacheas certain length of the tubing being fed to the coiling arm.

It has no other particular motor that it gears to. No position. So, I don't think MAM or MAG will work. But then isn't MAJ for manual jogging such as momentary push buttons by an operator?

 

[padees]

You can setup MAJ anyway you want. It just moves the axis until you give it a stop, and that can be from any source.

 

[MichaelG]

Questions to get better answers

The arm does it perform multiple wraps?
Do you want to rewind using torque (must maintain a particular tension) in the product?

When the coiler stops what happens to the product feed?

 

[unsaint32]

You can setup MAJ anyway you want. It just moves the axis until you give it a stop, and that can be from any source.

So, I can use MAJ for this application then. I thought MAJ is strictly for jogging in the traditional sense of "jogging"-while a human finger input is held.

Thanks.

 

[unsaint32]

The arm does it perform multiple wraps?

Yes, multiple wraps. Usually the tube length is 100' and the arm's spool diameter is about 8' so about 12 turns.

Do you want to rewind using torque (must maintain a particular tension) in the product?

Yes, constant torque would be nice.

When the coiler stops what happens to the product feed?

The coiler speed influences the product feed motor, so when the coiler stops, the product feed stops. There is an accumulator between the two that maintains an optimum slack.

 

[MichaelG]

ok some ideas for you
MAJ is a command for running the motor at a known speed

Multiple wraps
I may not have explained myself correctly
a) does the second wrap lay over the second wrap, increasing the radius of the
drum so needing the centre wind to slow down to keep the same tension in the product.
In this case the servo speed must slow down for each wrap to maintain tension
b) Does the second wrap lay next to the first wrap increasing the drum width and maintaining the same radius
In this case the servo speed stays the same for each wrap


You have mentioned an accumulator can you provide a diagram of the tube path from payoff to wind
It all has an effect of what is recommended and how to control
Note the accumulator may also provide the constant tension required

 

[kekrahulik]

Just to clarify...

MAJ is very much NOT like a jog that you hold a button for. When you trigger an MAJ instruction, the servo will run at the MAJ speed. The MAJ does not need to be kept on or true or enabled - the one time trigger starts the servo running. It will not stop until you issue a MAS instruction to make it stop.

So it is actually more like a sealed in run - press the start button and it runs until you press the stop.

BTW - if you want to change the MAJ speed after it has started, you will need to issue a MCD(Motion Change Dynamics) command.

 

[unsaint32]

Just to clarify...

MAJ is very much NOT like a jog that you hold a button for. When you trigger an MAJ instruction, the servo will run at the MAJ speed. The MAJ does not need to be kept on or true or enabled - the one time trigger starts the servo running. It will not stop until you issue a MAS instruction to make it stop.

So it is actually more like a sealed in run - press the start button and it runs until you press the stop.

BTW - if you want to change the MAJ speed after it has started, you will need to issue a MCD(Motion Change Dynamics) command.

Can I change the jog speed after it started by simply changing the value of the tag that I assigned to the speed parameter of the MAJ?

 

[unsaint32]

ok some ideas for you
MAJ is a command for running the motor at a known speed

Multiple wraps
I may not have explained myself correctly
a) does the second wrap lay over the second wrap, increasing the radius of the
drum so needing the centre wind to slow down to keep the same tension in the product.
In this case the servo speed must slow down for each wrap to maintain tension
b) Does the second wrap lay next to the first wrap increasing the drum width and maintaining the same radius
In this case the servo speed stays the same for each wrap


You have mentioned an accumulator can you provide a diagram of the tube path from payoff to wind
It all has an effect of what is recommended and how to control
Note the accumulator may also provide the constant tension required

AS you probably figured out, I am a very novice in PLC programming especially motion. I am a newbie maintenance guy. This project is just at the R&D state, when this project gets at full speed, engineers will re-program. Needless to say, I am not allow to share any diagram. But the accumulator laser is AI source; from 3 to 20 to indicate the depth of the tubing slack. The AI value will be used in some math instructions so that deep slack will cause higher speed of the recoiling arm.

Each wrap will have about 5 tubes and about total of 4 wraps. So, every time a wrap feed traverse (sorry I didn't mention this) changes direction, the speed will increase accordingly but not too much so not to lose the tension.

Thanks.

 

[MichaelG]

Can I change the jog speed after it started by simply changing the value of the tag that I assigned to the speed parameter of the MAJ?

no you need to retrigger the MAJ again with the new speed

 

[unsaint32]

no you need to retrigger the MAJ again with the new speed

Ok, when a row of the wrap is done, I need to MSO the MAJ then trigger the MAJ again with different direction. Now I get it. Thanks.

 

[kekrahulik]

You can almost think of the servos like playing "Simon says". You tell the servo to do something with a motion instruction once and it will do exactly that until it gets another motion instruction, but it does not keep watching that motion instruction or the tags in it.

So changing the value of the velocity tag of the MAJ will have no affect. The servo will keep doing what that MAJ told it to do at the time the MAJ was issued.

You can give another MAJ command or use the MCD command to change the current velocity, accel, etc of the servo.

The same will be true for MAS commands. Do not think of it like a stop signal of a regular drive - holding the MAS true(enabled) will not keep the drive from running. It is a one time command to stop. If it receives another command to move, it will move...and it doesn't have to wait for the stop command to complete.

 

[unsaint32]

You can almost think of the servos like playing "Simon says". ..... The same will be true for MAS commands. Do not think of it like a stop signal of a regular drive - holding the MAS true(enabled) will not keep the drive from running. It is a one time command to stop. If it receives another command to move, it will move...and it doesn't have to wait for the stop command to complete.

Things are much clearer to me now. Thank you so much.

 

[padees]

Think "one shot" to initiate a motion command.

I'm running in a gearbox on a new machine I'm building. I have the MAJ set up with a MAS. Hit the momentary button, it issues a MAJ, release the button, it issues a MAS. Typical Jog. For running in the gearbox I put a toggle button on the screen.

With the MAJ toggled in, then issue a MAM, it executes the MAM and stops in position.