1762-of4 no voltage at output

Hello,

i have a 1762-of4 connected to a ml1100. i setup an scp instruction with
n7:0
min 0
max 32760
scaled min 0
scaled max 10
output O:1.0

i know the analog card produces a 0 to 10v signal and want to use this to control the speed on a vfd.

when i run the program the output changes 0 to 10 but when i use my meter to check the output at vout0 and the common i dont get any voltage. the configuration for channel 0 is set to 0-10v raw/proportional. i took a look at the data table and i am only seeing the first 3 bits of O:1.0 change and according to the manual the output data should be on bits 3-14 but all these remain 0.

can someone provide some assistance, i wonder if my scp instruction is incorrect.

thanks,
Ricardo

Can you post your program? Its .RSS file , zip it first.

when i run the program the output changes 0 to 10 but when i use my meter to check the output at vout0 and the common i dont get any voltage.

Click to expand...

???? how do you know the output changes 0-10v?

From your description it sounds like you are sending the number 0 - 10 to the output. The module is expecting the numbers 0 - 32767. Since it is 12 bit you won't see anything at all until you get to 8 since the first three bits are ignored. So start outputting these higher numbers (e.g. 16384 should give you about 5 volts, you should see 10 volts at about 32760) and see what you get. In other words just MOV the value in N7:0 directly to O:1.0

If you are using the numbers 0 - 10 in N7:0 then your SCP instruction should be

n7:0
min 0
max 10
scaled min 0
scaled max 32760
output O:1.0

I know the analog card produces a 0 to 10v signal and want to use this to control the speed on a vfd.

Click to expand...

As Bernie pointed out, it is the analog output module that does the conversion from Digital Number to Analog Voltage. The Output in your PLC program therefore must be a digital number scaled to the range of numbers that the analog output module will accept.

You had the right numbers, but put them in the wrong places in your scaling equation!

If you are using the numbers 0 - 10 in N7:0 then your SCP instruction should be

n7:0
min 0
max 10
scaled min 0
scaled max 32760
output O:1.0

Click to expand...

Gosh, I completely missed that.

Another thing to consider is if using 0-10 to 0-32760, that will give you 10% incremental changes in your output. You may want to use 0-100 ( 1% changes) or 0-1000 ( .1% changes).

Or use a floating point data type as your input to the SCP instruction.

Your system will dictate.