Scaling

[glpdrumerx]

Hello everyone I am setting up a drive for a test line here. there are a couple of parameters where I have to adjust the scaling. I have never really had to adjust it in any of our machines because they are set when they come in. is there a site that explains scaling or can anyone just help me. I hate to sound so dumb but if you don't know then you just don't know.

 

[JHarbin]

Hello everyone I am setting up a drive for a test line here. there are a couple of parameters where I have to adjust the scaling. I have never really had to adjust it in any of our machines because they are set when they come in. is there a site that explains scaling or can anyone just help me. I hate to sound so dumb but if you don't know then you just don't know.

We're going to have to know a little more, especially which brand/model PLC/Controller you are using.

 

[glpdrumerx]

it is a control techniques unidrive classic 2402

 

[Ron Beaufort]

be careful what you ask for ...

is there a site that explains scaling?

for "scaling" in general, download the TWO PART "Scaling" papers from the Sample Lessons page of my website (link below my signature) ... the examples are mostly for Allen-Bradley - but the math concepts should be very helpful to you ...

tip: if this is more than you really wanted to know, then post again and tell us the exact range of values for your "inputs" - and the exact range of values for your "outputs" ... we'll be glad to calculate the appropriate scaling equation from that information ...

 

[DickDV]

Are you referring to adjusting the input analog speed signal scaling, the analog output scaling, or the overall speed ranges the drive will be capable of?

If you are referring to input or output analog, we will need to know what the signal is you are coming in or out with, and we will need to know what the drive input/output considers to be the 100% or full range.

 

[mordred]

also it would help to know what PLC your controlling the drive from. As DickDV mentioned we need details on how you wish to control it. Many drives can pass a message or using an analog external reference. Which describes your application? We need to know what types of signals your drive accepts or you prefer. and what analog output signals your PLC can generate as well

 

[glpdrumerx]

we are using a pot to set the desired speed,analog input 0-10 vdc we have an encoder 1024 ppr, using the PID within the drive and it's output can be scaled into a parameter for feedback of the line speed. I want to use the analog output, 0-10 volts or 4-20 ma to show actual line speed.

 

[DickDV]

I'm not directly familiar with the CT products but, generally, no scaling is needed for a 0-10V speed pot input signal. You do need to tell the drive what speed 0v represents and what speed 10v represents but that is all for the input.

Normally, drive analog outputs default to either 0-10V or 4-20ma with the minimum being zero speed and maximum on the range being maximum speed. No scaling needed here either unless you want something else (2-10V, 0-20ma, 0-5v, etc.)

Usually scaling adjusts the maximum end of the signal range and offsetting adjusts the minimum end. So, for example, a 2-10V signal has a 20% offset on the bottom and 100% scaling on the top. A 0-5v signal would have no bottom end offsetting and the scaling set at 50% on the top. A 1-6V signal would have 10% offset and 60% scaling.

Unfortunately, while what I've described to you is common, it may not apply to your specific drive. Quality time spend in the instruction manual is the only way I know of to determine with precision what you've got.

 

[tonye]

http://www.emersonct.com/download_usa/literature/UniSP0to6UGiss12.pdf

Above is a link to where you can get the user manual.

Looking at Menu 7 of this manual, you have by default terminal 9 configured for speed feedback.
All that is required of you is to acertain the mode of operation your unidrive is and program to parameter to match it, connect your output device according and you are set to go.
An Example:
If your unidrive is configured for Close Loop Vector and say your have an output device for speed indication with data " input signal 4-20mA, display range 0.000-1500rpm"

Then,

Set Parameter 7.19=3.02
" " 7.20=1.00
" " 7.21=1
connect the output device and your are ok.

Parameter 7.19 (Analog output1 source parameter, any parameter can be a source)
Parameter 7.20 (Analog output1 scaling, range 0.000-4.000, it is for gain control)
Parameter 7.21 (Analog output1 mode selector range: "0=Volt", "1=0-20mA", "2=4-20mA" and "3=H.Spd").

 

[glpdrumerx]

thanks everyone for all your help