Encoder Implementation

waterbottle

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Join Date
Mar 2019
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Hello Forum,


Looking for ideas of what can be the most practical implementation to a machine to add a feature of automated setup.
I explain....
<Machine will need to move a vertical screw to accomodate different size of bottles. the screw already has a motor that operates manually with a push button for up and down movement wired to a contactor> The setup does not need to be high speed opertion it will only need to be done during product changes

Current options Machine has AB CPU v17

Encoder over ethernet IP attach to current motor.... Expensive:p
VFD with encoder for position
Replace to servo and add kinetic drive
Add encoder to input card with gray code


I will really like to explore the powerflex with encoder for position since i will have to add vfd to slow down motor for accurate position.

If you guys want to share any ideas or any recommendations will be highly appreciated.
 
<Machine will need to move a vertical screw to accomodate different size of bottles. the screw already has a motor that operates manually with a push button for up and down movement wired to a contactor> The setup does not need to be high speed opertion it will only need to be done during product changes

In it's present implementation does the operator "hit the mark" with a single push button push, or is jogging needed?
 
Hello Forum,


Looking for ideas of what can be the most practical implementation to a machine to add a feature of automated setup.
I explain....
<Machine will need to move a vertical screw to accomodate different size of bottles. the screw already has a motor that operates manually with a push button for up and down movement wired to a contactor> The setup does not need to be high speed opertion it will only need to be done during product changes

Current options Machine has AB CPU v17

Encoder over ethernet IP attach to current motor.... Expensive:p
VFD with encoder for position
Replace to servo and add kinetic drive
Add encoder to input card with gray code


I will really like to explore the powerflex with encoder for position since i will have to add vfd to slow down motor for accurate position.

If you guys want to share any ideas or any recommendations will be highly appreciated.

DISCLAIMER: I don't use encoders at work. All of our VFDs are running in V/Hz or the flavour of sensorless Vector that each of the vendors use (siemens, Rockwell, Mitsubishi).
I use encoders on home-built VFDs for driving small vehicles - when I get time. The environment is about as noisy as you get. 3 phase unshielded motor cables driven by PWM a few inches from the encoder signals ... and the encoder signals at similar frequencies to the switching of the VFD. The general encoder stuff applies - shielded cables, short line lengths, and transient voltage suppressions if the lines are over about 10 feet

That said, the ethernet encoder will likely give a good signal. You can have extremely short line lengths that don't cross your 3 phase power cables if you are careful. Low latency on the ethernet/ip network, multiple vendors to choose from, a selection of resolutions available. The problem here is that you need the VFD anyway to limit the torque .. or figure out some other way to detect that your machine has made contact with the bottle. This would be where I would start if I were doing this at work.

The VFD with encoder tightens the loop between VFD and encoder, but (last time I checked) it would need to be hard-wired to the VFD, not etherent/IP. So line length is a potential problem. I don't believe that you get raw access to the encoder signal on the powerflex unless you use the 755 with the PLC built in. I'm sure that others will chime in with good info on that.

The servo and kinetic drive seems like overkill, but I would expect that to be quite reliable and easy for others to figure out what you did. I don't know what the torque limit settings are like on the kinetic.

The encoder to the PLC input would be cheapest. If your line length and resolution support it, it makes the most sense for you to troubleshoot it. It's where I would start if it were my money funding the project. But not if reliability is your #1 priority

Can you use a capacitive sensor to detect when the machine contacts the top of the bottle? Like an auto bed leveller for your CNC machine? If so, you may not need a VFD at all .. depending on how tight your tolerances are for the size of the bottle.
 
DISCLAIMER: I don't use encoders at work. All of our VFDs are running in V/Hz or the flavour of sensorless Vector that each of the vendors use (siemens, Rockwell, Mitsubishi).
I use encoders on home-built VFDs for driving small vehicles - when I get time. The environment is about as noisy as you get. 3 phase unshielded motor cables driven by PWM a few inches from the encoder signals ... and the encoder signals at similar frequencies to the switching of the VFD. The general encoder stuff applies - shielded cables, short line lengths, and transient voltage suppressions if the lines are over about 10 feet

That said, the ethernet encoder will likely give a good signal. You can have extremely short line lengths that don't cross your 3 phase power cables if you are careful. Low latency on the ethernet/ip network, multiple vendors to choose from, a selection of resolutions available. The problem here is that you need the VFD anyway to limit the torque .. or figure out some other way to detect that your machine has made contact with the bottle. This would be where I would start if I were doing this at work.

The VFD with encoder tightens the loop between VFD and encoder, but (last time I checked) it would need to be hard-wired to the VFD, not etherent/IP. So line length is a potential problem. I don't believe that you get raw access to the encoder signal on the powerflex unless you use the 755 with the PLC built in. I'm sure that others will chime in with good info on that.

The servo and kinetic drive seems like overkill, but I would expect that to be quite reliable and easy for others to figure out what you did. I don't know what the torque limit settings are like on the kinetic.

The encoder to the PLC input would be cheapest. If your line length and resolution support it, it makes the most sense for you to troubleshoot it. It's where I would start if it were my money funding the project. But not if reliability is your #1 priority

Can you use a capacitive sensor to detect when the machine contacts the top of the bottle? Like an auto bed leveller for your CNC machine? If so, you may not need a VFD at all .. depending on how tight your tolerances are for the size of the bottle.



The machine is a labeler from Krones. The setup will be completed without bottles in the machine. It will need to move the screw that moves the plates that bottles ride on up and down depending on the bottle size is being produced. Torque it wont be an issue. All I will need to accomplish is automatic change from one bottle size to the other consistently change after change and leave operator setup error out of question/
 
In it's present implementation does the operator "hit the mark" with a single push button push, or is jogging needed?


Currently the machine has a metric tape that indicates position and operator has to hold the button manually to the setpoint that is written in the setup sheet.
 
Honestly, spend the money on an ethernet/IP encoder and save your $ on development time. With a 140M-E encoder you'll have it up and running so fast that unless your time is worthless, I'd almost guarantee it'll work out cheaper in the long run. Spend on the hardware, save on the software, as one of my customers says (which is why they're my favourite customer).

If you really need to save cost, you could do it the way my, er, "less-favourite" customer does things and put a prox on the shaft to count pulses. You'll need to make sure the shaft is rotating slow enough (and your flag is wide enough) that the PLC can properly count all the pulses, and you'll need to take the direction into account, and allow for overrun. You'll also need to allow for calibration and scaling of pulses-distance. I've done the logic for this several times, and it's 100% doable, and has without exception worked out more expensive in the end than spending the money on an ethernet encoder and saving all my development time.
 
Some years ago a colleague of mine added an encoder to the same make of machine, I was not involved in the project but all that was required was the encoder + some engineering to fit it and the fitment of an HMI, an inverter was added to the drive but only to slow it down when approaching setpoint + a home position sensor. The positions were stored in recipes on the HMI (well I believe in the PLC but accessed by the HMI). This worked perfectly, there was no need to add anything else, the speed was slow enough to catch all pulses so was a complete success with moderate costs.
 
If the operator currently adjusts it manually with push buttons it seems that not much precision is required.

You can connect the encoder directly to PLC inputs and move the screw up and down by simple comparison of position and setpoint with some dead band
 
Honestly, spend the money on an ethernet/IP encoder and save your $ on development time. With a 140M-E encoder you'll have it up and running so fast that unless your time is worthless, I'd almost guarantee it'll work out cheaper in the long run. Spend on the hardware, save on the software, as one of my customers says (which is why they're my favourite customer).

If you really need to save cost, you could do it the way my, er, "less-favourite" customer does things and put a prox on the shaft to count pulses. You'll need to make sure the shaft is rotating slow enough (and your flag is wide enough) that the PLC can properly count all the pulses, and you'll need to take the direction into account, and allow for overrun. You'll also need to allow for calibration and scaling of pulses-distance. I've done the logic for this several times, and it's 100% doable, and has without exception worked out more expensive in the end than spending the money on an ethernet encoder and saving all my development time.


Absolutely,

Purchased and encoder from AB 842E-SIP12BA. Hopefully this does the trick quick ill be installing this week
 
Absolutely,

Purchased and encoder from AB 842E-SIP12BA. Hopefully this does the trick quick ill be installing this week
842E-SIP? Shouldn't you be using a multi-turn encoder for this, rather than a single turn? I mean, you can use a single turn and handle the rollover in the PLC if you want, provided it's rotating slow enough, but it'd be far easier to use a multi-turn encoder.

Also side note, I see that I managed to use the product code for AB circuit breakers (140M) instead of encoders (842E) in my original post. Clearly there was a short circuit somewhere in my brain that day.
 

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