analog out voltage

fritz

Hello nimalak

not too sure ifI understand your question correctly, but I'll have a stab at explaining whatI think it is anyhow:
A current Analogue Output (e.g. 4-20mA) will make sure to "drive"the requestedcurrent through the output.
Example:
Your Analogue device has a total "burden" resistance of 200 Ohm's (incl. cabling, terminal strips resistance etc.).
You use a 4-20 mA Output and set the Analogue Output to 50%.
The card will now "drive" 12mA through theloopfor which you will measure 2.4 V at the Analogue Output (200 Ohms * 12mA = 2.4V).
If your burden resistance changes (e.g. bad connections), the Analogue Output will maintain the 12mA current by changing the Voltage at the Output (this is a big advantge of current AI's and AQ's over voltage AI's and AQ's).
It can however only do so up to a maximal permissible overall burden resistance (typically 500 Ohms for an AQ, these values can be found in the product manual e.g. SIMATIC S7-300 S7-300 Module data.Note too max. open circuitOutput voltage of the AQ which typciallynot exceeds 18V).

I hope this helps