AB 1756-OF8 load questions

I have a OF8 Im trying to connect to a Bulliten 160 drive. Im using 4-20ma. The resistance across the 160 input is 500 ohm. Do I have to put a resistor across the input to get it higher?

I read somewhere that it has to be above 2k? Is this right?

Thanks

No, the 4-20mA output from the OF8 can directly drive that input, as long as you are indeed using current loop.

The drive capability of that module for current loop is listed at 0 to 750 ohms. The 2K+ minimum limit is only for using voltage outputs.

rdrast said:

No, the 4-20mA output from the OF8 can directly drive that input, as long as you are indeed using current loop.

The drive capability of that module for current loop is listed at 0 to 750 ohms. The 2K+ minimum limit is only for using voltage outputs.

Click to expand...

Strange, I did hook it up directly using ch1 4-20ma and it just sinks the signal. I can see the drive in networx for DN and Im just getting .3Hz when I can see that CH1 is ast 100% via logix. Do I need to use a external 24vdc supply? I already have a Watlow Din a Mite hooked to Ch0 directly. Am I missing something? Im used to the IF16 but never did a OF8.

The 4-20 is connected to TB3 3 com to OF8 rtn and TB3 4 to OF8 Ch 1 I

Thanks again

First, No you dont need an external power supply. Maybe step back and put an meter on it and see what you get across a load? Also check your faults and status for the card.

I am not sure I understand your last sentence on your connections. This is what I see you doing:

TB3: IOUT-0 (channel 0)
TB5: RTN

TB4: IOUT-4 (channel 4)
TB6: RTN

If that is how you have it wired and that is your channel designations then all should be good there. I am confused by your mention of Channel 1.

Well after putting in 1900 of sensor offset it works....sort of. I only have about a 4hz span that it controls

I got it...darn PID wasnt set up all the way.....

By the way what are some good PID settings for a flowmeter controlled pump?

Thanks again for your help!

sts2ss said:

I got it...darn PID wasnt set up all the way.....

By the way what are some good PID settings for a flowmeter controlled pump?

Thanks again for your help!

Click to expand...

The ones that work.
Seriously.
There is no "Magic Set Of Numbers" for PID's.
Search here for PID, read some of Peters (and others) posts.

^ what rdrast said..

I have 2 loops running our Ballmill here. One running off a sound level and one off a massflow.
2 totally different sets of PID settings in order to get the right response.(and the 2nd one didn't like the 'guessed' settings at all the first time)

I turned our loops manually using some realtime trends.