Created Date: January 10,2010

Created by: KPrice

Basscat, since you know your raw output is 65535, I would next check the loop current. If you are getting 20.00 ma, then it's your VFD input or VFD scaling. If you 're getting about 19.97 ma, then it's your module, or high resistance in your loop somewhere. But the 0.1 Hz is 0.17% of 60HZ. Is there a Hz tolerance that your VFD can control to, +/- %? And display to, +/- 1 digit? Temperature can affect the tolerance. If you need to "adjust " the display, so it "looks " right, can you tweak or offset the VFD scaling?

Created Date: January 11,2010

Created by: Basscat

KPrice thanks for your input. All of what you stated i have thought about except i have a blown fuse in my meter so as of now i can't check the loop current but i will get that fixed and check to see what it is. All of the connections are good because about 3 days ago it was reading 60 Hz and that was in my shop and the temp has been up and down in there and it was reading the same. As for the scaling i am trying to figure out if there is an offset to the drive it's not being very explanitory as far as that goes. But i appreciate your info on the subject i was just wondering if there was anything that i wasn't thinking of that would cause this little inconvenience. Thanks Again

Created Date: January 11,2010

Created by: KPrice

Basscat, that is strange that "3 days ago it was reading 60 Hz ". It read 60Hz in your shop, you installed it in the field, and now it reads 59.9Hz. Some thoughts on field installation. Loop resistance low? Good 18AWG twisted-pair, shielded cable w/ shield drain wire grounded on one end? Good grounding/bonding of PLC cabinet, VFD cabinet, VFD driven device (pump), conduits, etc? Accurate loop current will tell us which way to look.

Created Date: January 11,2010

Created by: Tinker

.1 of a Hert is not alot but in this case it really matters.

I'm curious why it really mattters, is is it cosmetic or do you really need an exact speed, the latter, are you using an encoder feedback? I can't imagine controlling speed to within 0.2% without it, but then that is not my field of expertice.

If it is cosmetic, then adjusting the input so that 20mA coersponds to a slightly higer frequency than 60Hz and letting the letting the the max speed setting limit it to 60 shold give a steady 60Hz display. However there will be a deadband when reducing the speed from maximum, so one would want to keep the offset to a minimum. I'm not familiar with the PowerFlex, I just have a PDF of the manual I downloaded from Rockwell, and I agree with "not being very explanitory " but you might want to look into parameters 091 and 322.

BTW, 0.17% is less than the rated maximum inaccuracy of your output module, also less than the accuracy of many low to mid range multimeters, even the $500 FLUKE 771 process meter is only rated for 0.2% + 2 counts, though it is a sort of a special case, being a clamp on mA meter.

Also, while the display is reading 59.9, the actual frequency could consivably be very nearly 59.95, less than a 0.1% devation, which makes forcing the display to 60 and living with a small deadband look more inviting than trying to make 65535 = exactly 60.0Hz

Created Date: January 10,2010

Created by: Basscat

Hi to all

I hope everyone is having a great new year

I was hoping someone can help me. I have set up this F0-04DAH-1 4-20 output module and everything was working fine. But now when i set a math-binary instruction of 65535 my VFD doesn't read 60 Hz anymore it reads 59.9 Hz. and i have the VFD set to a maximum freq of 60 Hz. And also in the data view the output reads 65535 but the VFD doesn't produce 60 Hz. The VFD brand is AB Power Flex 70. Can someone help me figure out why. Also i know

.1 of a Hert is not alot but in this case it really matters. All replies would be greatly appreciated. Thank You