ab 1305 vfd scaleing to plc

I really dont understand how the comm / control works with 1746 l542b w ni4v analog tring to control my motor. 7.7amp (460) max motor = 1725rpm. o bit (on ni4v) = amp and 3 = rpm How to get 500rpm?? Thanks.

Several steps in the scaling sequence

More complete descriptions of your questions will help you get better information from this Forum. Your current posting is pretty difficult for me to understand.

The 1746-NIO4V is a combination input/output analog module for the SLC-500 family of controllers. The module can send out between 0 and 10 volts on each of its output channels.

The Allen-Bradley 1305 AC drive can put out between 0 and 400 Hz AC sinewaves to control induction motors. Very simply, your motor will spin at about 1725 RPM when the sinewave from the drive is at 60 Hz.

Since you want to run the motor at 500 Hz, you need the drive to put out (500 / 1725 * 60 = ) 17.4 Hz.

NI4V doesn't ring a bell. Could it really be a NO4V? NIO4V?

And, welcome to the forum. By the way, you'll get best results when you make whole sentences with correct spelling.

Paul

Normally, any AC drive with an analog input will scale the full analog range (0 to 10 V) to the nominal range between zero and full speed (0 to 60 Hz).

So we use another simple ratio equation. 17.4 / 60 = x /10

x= (17.4 / 60) * 10 = 2.9 volts.

We're almost there. Now you need to know what actual value to put in the Output data table of the 1746-NIO4V module.

For that, we go to the 1746-NIO4V User Manual, Publication 1746-UM005, on page 4-8. The output of the NIO4V module scales to between 0 and 32767 for 0 to 10 Volts DC.

x / 32768 = 2.9 / 10

x = (2.9 / 10 * 32768) = 9503

So the simple answer to "what value do I put in the output register to get 500 RPM" is "9503".

Search this site for help on the Scale With Parameters (SCP) instruction that helps simplify this math in the SLC-500 controller.

You may also have to review the parameters of your AC drive to be sure that the maximum output frequency is set for the default of 60 Hz rather than something else like 90 or 120 Hz.

Welcome to the forum !