4-20 ma or 0-10vdc

[joey791]

Originally posted by lonboy
Let's see.... PID is an acronym for Perplexing, Intimidating, and Difficult. In most cases if you leave off the D it works pretty well.....
Now that we have that cleared up, what do you want to drive from the CV output, what and where is your PV input, and how are you adusting the SP?

-Lb

No PID stands for Pretty Intense Destruction

[sysint]

Originally posted by joey791

Originally posted by lonboy
Let's see.... PID is an acronym for Perplexing, Intimidating, and Difficult. In most cases if you leave off the D it works pretty well.....
Now that we have that cleared up, what do you want to drive from the CV output, what and where is your PV input, and how are you adusting the SP?

-Lb

No PID stands for Pretty Intense Destruction

-See tmk wouldn't it have been easier to read that little Honeywell manual instead of attempting the easy way out?

Lonboy, Joey, etc... You guys are really coming through... Thanks!

[cleancondenser]

4 to 20 ma is immune to electrical noise and
long wire runs that cause voltage drops
You can convert it to voltage
the same way the fire detection systems with smoke heads do
place a resistor accross the line and read the voltage
Yes 10 Volts D.C is much easier to read

[emjay]

I thought I would throw my 2 cents into this.

The main reason to use 4-20 madc loops is that current is common in series. A current loop holds it's accuracy over long distances, where the voltage drops on long wire runs. This is why the chemical/oil/instrumentation business has been standardized on 4-20madc (and occasionally 10-50madc) loops for over 30 years.

For those who want to trouble shoot in voltage, you can use a 250 ohm resistor in series with a 4-20madc loop and measure 1-5vdc across it to get scale readings. Most receiving instruments (devices that receive the 4-20madc signal) have shunts built into their electronics, so sometimes it is possible to measure at the terminals of the device and see a scaled voltage signal.

FWIW

[tmk]

Hey Thanks alot fellas!! You've been very helpful.