Click Analog Output Always On?

[NewGuy2024]

I have a program that I am gradually piecing together (my first program).
There are 4 cascading timers that turn Y001 and Y001 + Y002 on and off, then repeat for XX cycles using a counter before resetting to start. Another non-resettable counter monitors total count.
During each sequence of cycles I have output Y003 on constantly, I also have an analog output voltage form DA1V, set using DF3 in a math instruction. I can vary the output voltage using a C-more micro HMI no problem.
My issue is I want the analog output to only be on while a counter sequence is running (same as Y003), at the moment it is on constantly so long as the PLC is powered up. I am thinking I might need a copy instruction but I am not sure how to structure it - see attached picture for current rungs.

 

[OkiePC]

If you want the analog output to have 0 vdc when Y3 is off, then you'll want to add a branch to your rung that writes a constant to it and condition it as such. You can use the CPD or Math instructions. I'd recommend changing the constant to a retentive float so that you can simply edit its value at runtime. Matter of fact, I would do that for both values.

What if in real life, an output of 0.1 vdc works better than zero? Do you want to have to perform a runtime edit of the logic or simply adjust the "off" value in a dataview or HMI?

 

[drbitboy]

What @OkiePC said.

[update: fixed typo; note that adding a NC Contact reading the value of Y003 on the first rung would also work and might be easier to read and grok]

 

[OkiePC]

Too late to edit but where I said CPD (Copy Data) it should just say Copy instruction. For the options just use Copy Single and pick a source address.

 

[NewGuy2024]

Thanks drbitboy, I tried your suggestion (with and without Y003 NC contact) and all I get now is no analog output voltage at any state.

OkiePC, I am not exactly sure what you are proposing, I did wonder if it might take a copy command, the attached picture is how I got a counter output to display on the HMI, I imagine something along the same lines.

For context, imagine a blind-folded man arms out in a dark tunnel trying to find the way out, that's me trying to program!

 

[OkiePC]

OkiePC, I am not exactly sure what you are proposing, I did wonder if it might take a copy command...

Something like this to manipulate the analog output. This assumes that DF3 writes to the proper channel of the analog card to control the brake and that the scaling suits your needs.

The Data View allows you to edit the values in a PLC address without having to edit the logic. This only works for values that aren't being overwritten by other PLC functions or programming. My screenshot is an example that is not online with a PLC so it shows no current values.

 

[NewGuy2024]

Thanks OkiePC, I will give this a try.

Just to make sure I fully understand DF10 will always be 0 (off), DF11 will be variable 0-5V set by the HMI?

 

[NewGuy2024]

I had to swap the NC and NO Y003 contacts but it now works as I need.

Thanks all.

 

[drbitboy]

Thanks drbitboy, I tried your suggestion (with and without Y003 NC contact) and all I get now is no analog output voltage at any state.

Huh, that's surprising, because the version with the Y003 NC contact should be the same as what @OkiePC suggested, and that worked. Oh well, here's to dark tunnels; I'm glad @OkiePC got you going!