Yaskawa PLC: Motion Question

I have a question regarding Yaskawa PLC motion programming. I’m working with a somewhat old program on a Yaskawa PLC which I am not very familiar with. From what I’ve read, all motion commands are completed via motion programs, programs that are called from the ladder program. However, the program I’m working with does not have any motion programs for controlling the axes. I find this odd.

I’m curious if there is a way to control axes (specifically a virtual axis) without needing a motion program. Is that possible? Or does there need to be a motion program and I’m most likely missing it?

Any help would be appreciated.

yea that is a bit odd if you can't find the code to control the axis, i have attached a link on youtube that has a wealth of info on yaskawa motion hope this helps

http://www.youtube.com/results?search_query=yaskawa+motion+control&sm=1

Thank you very much, I’ve watched a couple of those videos and they appear to be pretty helpful. However, I have a few questions that you (or anyone else) may have the answer to:

1) In MotionWorks, will the virtual axis have axis variables located in the variable window? I know there is a virtual axis in this program I am reading, however, there doesn’t seem to be any variables in the variable window that says virtual axis anywhere.

2) How many virtual axes can exist on the SVR module?

3) If I were to write a speed command to a virtual axis, this would have to be completed via a motion program correct?

tomizzo11 said:

From what I’ve read, all motion commands are completed via motion programs, programs that are called from the ladder program.

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This is incorrect: using motion programs is just one of the methods of controlling motion in Yaskawa PLCs. Another method is to put proper values into certain output registers associated with each axis. There are registers for target position, velocity, accel, decel etc. and there is a a register for a motion command: positioning move, homing, constant velocity move, following move and few others. There are also input registers for each axis so its state can be monitored.

The specific information depends on the particular PLC model you are using as well as on the configuration of the axis in question.

LadderLogic said:

This is incorrect: using motion programs is just one of the methods of controlling motion in Yaskawa PLCs. Another method is to put proper values into certain output registers associated with each axis. There are registers for target position, velocity, accel, decel etc. and there is a a register for a motion command: positioning move, homing, constant velocity move, following move and few others. There are also input registers for each axis so its state can be monitored.

The specific information depends on the particular PLC model you are using as well as on the configuration of the axis in question.

Click to expand...

I just found this out yesterday! After digging around through the code, I realized this is how the motion commands were being sent. I then stumbled across relevant documentation that outlined the exact I/O registers that corresponded with motion commands.

You might be able to answer this question then: Is there any way to determine how many virtual axes are being used in a program? For real axes, you can see all of the structure instances under the axis variables tab in the variable window.

I know in the SVR module, it states that from I/O register 8000 to 8FFF is used for variable axes data. I also remember hearing that there is a possible of 16 axes. Would that simply mean that there are enough register addresses from 8000 to 8FFF to store data for 16 axes? All I want to know is how many virtual axes are being used.

Th eonly method I know is to go through each axis in SVR module configuration and to see which ones are set to "Axis used" - there are only 16 after all.

If you are using MotionWorks 6 with a MP2000 series PLC, you may be able to check which registers are being used in the program with register monitor: the addresses used are highlighted in color. Remember that each axis in Yaskawa PLC uses 128 input words and 128 output words, or 80 hex. So if your SVR module is configured as "circuit number 1" with starting address 8000h, any reference in the program to IW8000 through IW807F and OW8000 through OW807F would mean virtual axis 1 is being used; for axis 2 the IO range is 8080 through 80FF; axis 3 - 8100 through 817F and so on.

LadderLogic said:

Th eonly method I know is to go through each axis in SVR module configuration and to see which ones are set to "Axis used" - there are only 16 after all.

If you are using MotionWorks 6 with a MP2000 series PLC, you may be able to check which registers are being used in the program with register monitor: the addresses used are highlighted in color. Remember that each axis in Yaskawa PLC uses 128 input words and 128 output words, or 80 hex. So if your SVR module is configured as "circuit number 1" with starting address 8000h, any reference in the program to IW8000 through IW807F and OW8000 through OW807F would mean virtual axis 1 is being used; for axis 2 the IO range is 8080 through 80FF; axis 3 - 8100 through 817F and so on.

Click to expand...

Thank you! Everything is starting to make more sense now. I was primarily struggling with the help documents that were so hell bent on motion programs that I thought that was the only way. However, every piece of code I was reading was referencing the axis structures with the 80H offsets.

You seem to have a lot of knowledge regarding Yaskawa PLCs. Would you mind if I have a question in the future I PM you directly?

tomizzo11 said:

Would you mind if I have a question in the future I PM you directly?

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Not at all. Although I think an open discussion may benefit someone else who reads or may read this forum in the future.