4-20ma output

[bobnorway]

Using Visilogic V9.4.0 running WINXP sp3 .

V1040 with V200-18-E6B

Re-installed visilogic software, updated operating system on V1040,

created a new empty project, no change.

The V1040 has a 24vdc supply.

The problem is that the 4-20ma analog outputs (both channels)

seem to be limited to about 10volts.

This gives me a maximum loop resistance of 50ohms not the 500ohms

stated in the manual.

It would 'appear' that some software from a 0-10volt output is limiting the 4-20ma.

Test it yourself: hang a 100ohm load and set the channel for 4095 decimal.

This should work and give 20ma = 20volts but it doesn't, it'll stop at 11volts.

[Joe Tauser]

Umm... 500 ohms x 0.020 amps = 10V. My calculator says so, and it agrees with the point of your post. 50 ohms would give you 200 mA at 10V.

Joe T.

[AlexUT]

Hi,

Maximum load for current output is 500 ohm.

As Joe say, for 20 mA output current voltage at 500 oHm resistor is: V=R*I, V=500*0.020=10V. It never will be more.

And for 100 oHm resistor voltage should be 2V.

[bobnorway]

I'm embarassed.

My brand new box of 100ohm resistors is full of 1Ks.

Ohm's law rules here also.