Device Net VFD Speed Control

[Drewster1123]

Hello, So I was asked to turn up the speed on a VFD to allow a carriage to move a little bit faster and avoid getting stuck. Im not sure the exact VFD model but in the PLC logic it seems like there is a tag with the description "SPEED REFERENCE"

I came across an older post on the forum that mentioned the speed reference is 4 characters long for some VFDs and that is similar to what I'm seeing in the program here. the speed reference is set to 5000 and then after reaching a certain point it is slowed down to 2500 or 1250.

Is this the correct tag to change to speed up or down the speed of the VFD?

In the attached image it seems like there is a slow speed, medium and fast speed based on where the carriage is on the track.

appreciate the input.

 

[Ken Roach]

Thanks for posting that screenshot of the old thread. In that case, the phrase "4 characters long" really means that the units are 0.01 Hz instead of 0.1 Hz on two different models of VFD.

With the values of 5000, 2500, and 1250 being used in the PLC program, it is very likely that the Speed Reference is in units of 0.01 Hz.

5000 = 50.00 Hz
2500 = 25.00 Hz
1250 = 12.50 Hz

I can't say for certain; some VFDs used a span of 0-32767 = Min Hz to Max Hz, or other unit or scaling math.

But it's a fairly safe bet that those values represent the output frequency of the drive in 0.01 Hz units.

 

[alan_505]

Also make sure that the VSD you are using has the maximum speed set to the value that you want, if the VSD is currently set to 50Hz maximum and you want to run faster than this you will need to set it at least the value you want to run at.