FS: Keithley 10-Channel scanner card selfmade

[derZockerMP]

Hello, I want to sell my 10-channel scanner card for a Keithley 2000, DMM6500, 2010, 2001, or 2002.
€100 plus shipping

[derZockerMP]

Still avaiable

[derZockerMP]

Still some more avaiable.
Price drop to 90€ including shipping

[005]

Which microcontroller have you chosen?
Are source code, binary image and schematics available?
Are there any timing constraints due to the use of latching relays compared to standard 10 channel scan cards?

[derZockerMP]

The schematic and layout are not public, but I can send them to you if you purchase one. There is no built-in microcontroller. Regular shift registers are used here, which have the advantage of being faster, so they are also compatible with the 2001, 2002, and 2010 units because they have a higher clock speed. A standard microcontroller like most STM32s has a speed that is too low to communicate with the multimeter. Therefore, due to the shift registers, regular relays are used because SSRs, for example, have a different control scheme. I hope I was able to answer your question.

[voltsandjolts]

A standard microcontroller like most STM32s has a speed that is too low to communicate with the multimeter. Therefore, due to the shift registers, regular relays are used because SSRs, for example, have a different control scheme.

It's not speed that's the problem, as the spi peripheral in an mcu is a shift register that can be clocked at many MHz. On the Keithley 2001/2002 it seems that there is the possibility of an extra clock pulse on the bus, which can screw up data transfer to a spi peripheral. In essence, you need to extract the last 24 bits prior to the strobe pulse. This can probably be achieved in firmware but I don't have such a Keithley to test on, so haven't yet tried on my 20-chan card.

[voltsandjolts]

Your PCB has silkscreen text which says "before connecting the sub-d make sure the dmm is powered off". This is incorrect.

Because mechanical shock can open or close magnetic latching relays, you need make sure they are in the default open state prior to wiring, or at least prior to applying power to the equipment under test. Otherwise, closed relays can create a short circuit between multiple input channels.

To ensure the relays are in the default open state:

• Power off the dmm
• Insert the scanner card
• Power on the dmm

[derZockerMP]

Thanks for the explanation.
Yes, that's right, my fault.