Has anyone used a universal channel as a continous analog output? I've used output channel successfully with a CR3000 in the past but I'm not having much luck implmenting it with a CR6. The channel outputs the deseried voltage for a fraction of a second then goes to zero. I'm running a 1 second scan rate and I've tired a bunch of different delay values, includint zero. Also the example code in CRBasic Help does not turn the channel on (the delay is set to 200 microseconds).
If you use a delay of 0, the excitation channel is kept on only until all analog instructions within that scan are completed. There is not a continuous analog output function on the CR6 like the CAO port on the CR3000.
Thank you for your reply. Is there a way to program one of the CR6 universal channels to behave as a continous analog output?
The CR6 does not have any continuous analog output circuitry. You would have to use an external module such as the SDM-AO4A
The SDM-A04A looks like it would work well for my application. I'm already using op-amps with the output so I'm going to try setting them up to do "sample and hold" using mosfets and capacitors.
I set the port high pre the scan, seems to work
BeginProg
' pressure sensors, 5V from
PortSet(U8,1)' Excite 5v U8 for the Pressure sensor
Scan (1,Sec,0,0)
'Psensor Pmv reading
VoltSe(Pmv,1,mV5000,U10,1,0,50,Pmulti,Poffset)
NextScan
A Portset() will persist. However, it is not outputting a tightly regulated voltage.
If your sensor requires an excitation voltage, you should be using a bridge measurement instruction like BrHalf().
We use dataloggers for sensing and control. If it is possible to change firmware to allow the U* terminals to be deployed as continous analog voltage outputs this would greatly expand the versitilty of the CR6.
It is not a matter of firmware. The hardware does not exist in the CR6 for continuous analog output. That functionality can be added by connecting a SDM-AO4A or SDM-CVO4.