Programming Ramp Output on Rigol DP832

This is just a quick note to help those who might have trouble interpreting the instructions from Rigol for their awesome DP832 Programmable Power Supply Unit in order to get a ramp voltage.

I wanted to simulate the startup of a cheap switched mode wall wart DC power supply that was giving me trouble in a circuit. If I plugged the wall wart into the wall, and then the DC lead into the circuit, it worked well (step supply from 0V to 9V). When I plugged the DC lead in first and then applied mains to the wall wart, the circuit misbehaved. I thought my new Rigol DP832 might come into play here to automatically keep cycling through a simulation of the problematic startup conditions.

The point is that we want to program the unit to supply a ramp voltage up to the supply (9V). You can do this the hard way by manually entering the voltages for all the steps in the ramp, or you can use the Templet (sic) feature. At first I thought this was a typo, but the Oxford English Dictionary does offer ‘Templet’ as an alternative to the only version I’ve ever seen before – ‘Template’. For what it’s worth my spell checker doesn’t like ‘Templet’, either.

Enough Talk Already, This Is How You Do It

Select an output channel by hitting one of the large 1, 2 or 3 buttons. Then hit the Timer button. Then the Timer Set soft key, scroll through to page 3 and hit the Templet soft key. You can select the Type (in this case I wanted a ramp). Since I wanted a ramp that just went up, and then stepped down, I selected Symmetry and wound that up to 100%. A trap for young players: you need to set Current (here in this Templet menu) to a non-zero value otherwise the output will never switch on, since the default is always zero! I set Max Value to 9V. I set Points to 50 (Points being the number of steps the output will take in the cycle). I left interval at 1s which, very annoyingly, is the minimum period between steps (points) on the output. Once you’re happy with this, and here’s the other trap for young players, you need to hit the Construct soft key. I know it says this in the manual, but I didn’t find this vital step to be very intuitive. The Construct key fills in the ‘spreadsheet’ in the menu level above with all the points for the voltage (and current) output steps. Now when you hit the ‘back’ soft key from the Templet menu to return to the Timer Set menu, you’ll see your ramp (or whatever other shape you set up) on the little graph and also the point values in the ‘spreadsheet’. Now, finally, you’re ready to hit the soft ‘back’ key again to get to the top-level Timer menu and you can hit the Timer Off soft key to start the sequence (you may need to also hit the On/Off key for your channel to get this to start).

Easy, huh?

The 1s minimum period between steps in the output is a real pain, though. I might investigate whether I can get my PC to send the commands via USB, RS232 or LAN in order to get a rather more brisk ramp-up.

I’m running firmware 1.13 on a unit shipped in June 2015. It has all options installed thanks to help from the dark underbelly of the interwebs.