| Products > Test Equipment |
| DIY scan card for Keysight 34970A |
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| razvan784:
--- Quote from: bsdphk on May 29, 2022, 06:27:57 pm ---And the 8-slot device exists, I've seen it on ebay, can't remember then umber. --- End quote --- There is an 8-slot 34980A, but it is of a newer design, having an Ethernet interface and wider modules. Some time ago I also attempted to design a sort of test board for reverse engineering the protocol and to act as a base for custom modules. Unfortunately I did not find enough time/motivation to actually build it yet, but attached are the schematic and PCB in KiCad 6 format - maybe someone will find them useful. It is centered around an 87C52 MCU, just like the original modules. Theoretically it should work with a MCU pulled from a working module (some versions have them socketed) - I thought that would help the debugging / reversing effort. Also a pin header is provided to monitor and override serial communication. |
| strawberry:
AT89S52 seems compatible replacement |
| H.O:
I'm getting lost in my own notes... Sometimes, when being given a 0x109 command (for example during initialization or when manually opening/closing channels) the card responds with either 0x120 or 0x121. But other times (for example during a scan), it responds with 0x100 / 0x101 instead. Anyone been able to figure out the difference? (0xc8 >> 3) is likely the command to return reference junction temperature. I'm trying to figure out the data format but no luck so far. |
| voltsandjolts:
--- Quote from: H.O on June 01, 2022, 06:53:39 pm ---Sometimes, when being given a 0x109 command (for example during initialization or when manually opening/closing channels) the card responds with either 0x120 or 0x121. But other times (for example during a scan), it responds with 0x100 / 0x101 instead. Anyone been able to figure out the difference? --- End quote --- Yeh, that has been irking me a bit. My latest guess is that 0x121 ready (i.e. not busy) 0x120 busy opening relays 0x101 busy closing relays 0x100 ...hmm hadn't noticed that one --- Quote ---(0xc8 >> 3) is likely the command to return reference junction temperature. I'm trying to figure out the data format but no luck so far. --- End quote --- Yes, that starts off the read, getting a one byte response which is the LSB. The 3 remaining bytes are then read with the (0x48 >> 3) "read next byte in the transmit buffer" command. MSB last. Low 16 bits for ch1-10 CJ, high 16 bits for ch11-20 CJ. Exactly the same 4 byte transfer mechanism is used for the relay cycle counts. Looking at details of relay stuff now... At startup with genuine 34901A, the dmm sends (to card in slot 3) 1BB 000 000 000 010 Been trying to figure that out, thought it might have been fram or CJ related but no. It ties in with relay driver activity (U102 pin1 toggling), so must be reseting relays....but takes 1.7sec to complete ??? PulseView capture attached for anyone interested. Progress so far with my card: It gets recognised and I can read dummy values for CJ temperatures and the relay cycle counts. |
| free_electron:
since its a 85c52 ... anyone tried dumping it ? The guy from The Signalpath did it with the VFD display processor. |
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