Products > Test Equipment
RIGOL Support fading out ? What is your experience ?
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rsjsouza:

--- Quote from: Wolfgang on August 27, 2018, 08:07:15 pm ---... exactly. The schematics looks nice, but what they do is rip open the bridging relay before the connection to the multimeter current input (including the shunt) is established.
To me it looks like a beginners fault when programming the relay timing. Unfortunately, they refuse to work on this bug.

--- End quote ---
Wow, that is a pretty fundamental error which prevents usability.
Wolfgang:
I did. They gave me a M302 model to continue my tests. This is a voltage/resistance only card with 20 channels. I made a shunt resistor to measure the current via the burden voltage. We still have to negotiate how to proceed, I still have the right to return it.
Wolfgang:
... correct. I simply did not believe that they could be so silly. The M300 is on the market for a few years now ..  :--
2N3055:
Regarding M300, if you want switching between different inputs, connected to different circuits, you HAVE TO break before make.. Or you will shortcut different circuits...
Only way to do it without breaking is to have several shunts, one for every input. On schematic, there is something that looks like a short link. Maybe place for shunt?
Or you could have duplicate relay, that will make a short IN1, than brake IN1, make IN2, unshort IN2....

But you have to break one input before make other, otherwise BOOM...

What scanner card from other manufacturer can do switching of current measurements, using meter internal current shunts and that doesn't break before make?
That would be interesting info..
Regards,

Wolfgang:
... break before make for voltage inputs is fine and logical. The M300 always measures one channel fter the other, one by one.

For current channels it *should* work like this:
- leave input relay in bridge mode (see schematics)
- disconnect relay between input and meter for all current channels
- close connection from current channel to shunt inside meter
- open input relay and measure
- close input relay
- open connection from current channel to shunt inside meter

... next measurement.

If you are in autoscale mode, it would be OK if the lowest value shunt is tried first, but always with input shorted between shunt resistor changes, of course.

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