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| DIY scan card for Keysight 34970A |
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| H.O:
I hooked up the logic analyzer (to a 34901A placed in slot 1) and played around a bit. It looks like the baudrate is indeed 187500 but, to me, it doesn't seem to be 8E1 like with the front panel but a rather weird 9N1. First, manually closing/opening channels: Communication starts with the DAQ sending 0x109 to which the card responds with 0x121: Then the DAQ sends [COMMAND] followed [CHANNEL] where: COMMAND = 0x1E9 for CLOSE 0x1E1 for OPEN CHANNEL = 0x040-0x049 for channels 1 to 10 0x080-0x089 for channels 11 to 20 0x015-0x016 for channels 21 to 22. When the DAQ is in scan-mode things are a slightly different. First the DAQ sends 0x1D9 followed by the channel as per above. Then, after some delay (anything between 15ms and 1500ms depending on channel configuration) the DAQ sends 0x109 to which the card responds with 0x101. Obviously there's more to it than this but hey, it's a start :-) |
| strawberry:
boot up sequence, card sends card number and slot number(avoiding slot com conflict) 0x109 could be slot number |
| H.O:
I captured the bootup sequence with the 34901A in each of the three slots, no other cards: 34901A in slot 1 of 34970A: --- Code: ---At startup the uC RST-pin and the SRQ-pin is held high for aproximately 50ms. Then, after about 1400ms the following happens: DAQ sends 0x119 Card responds 0x101 DAQ sends 0x121 SRQ-signal goes high for 200ns, low for 16us and then high (where it stays) Card responds 0x121 DAQ sends 0x11A DAQ sends 0x11B 200ms of silence DAQ sends 0x169, 0x030, 0x000 Card responds 0x121 5ms of silence DAQ sends 0x169, 0x030, 0x000 Card responds 0x121 8ms of silence DAQ sends 0x1B9, 0x000, 0x000, 0x000, 0x010 170ms of silence DAQ sends 0x109 Card responds 0x120 DAQ sends 0x109 Card responds 0x120 DAQ sends 0x109 Card responds 0x120 DAQ sends 0x109 Card responds 0x120 DAQ sends 0x109 Card responds 0x121 --- End code --- 34901A in slot 2 of 34970A: --- Code: ---At startup the uC RST-pin and the SRQ-pin is held high for aproximately 50ms. Then, after about 1400ms the following happens: DAQ sends 0x119 DAQ sends 0x11A Card responds 0x101 DAQ sends 0x122 SRQ-signal goes high for 200ns, low for 16us and then high (where it stays) Card responds 0x121 DAQ sends 0x11B 200ms of silence DAQ sends 0x16A, 0x030, 0x000 Card responds 0x121 5ms of silence DAQ sends 0x16A, 0x030, 0x000 Card responds 0x121 8ms of silence DAQ sends 0x1BA, 0x000, 0x000, 0x000, 0x010 170ms of silence DAQ sends 0x10A Card responds 0x120 DAQ sends 0x10A Card responds 0x121 --- End code --- 34901A in slot 3 of 34970A: I've added some comments as to what I think is happening. --- Code: ---At startup the uC RST-pin and the SRQ-pin is held high for aproximately 50ms. Then, after about 1400ms the following happens: DAQ Sends 0x119 (polls slot 1) DAQ sends 0x11A (polls slot 2) DAQ sends 0x11B (polls slot 3) Card responds 0x101 (type of card perhaps, 101=34901?) DAQ sends 0x123 (attention slot 3?) SRQ-signal goes high for 200ns, low for 16us and then high (where it stays) Card responds 0x121 (ACK?) 200ms of silence DAQ sends 0x16B, 0x030, 0x000 (0x16B has something to with the slot, the rest no idea) Card responds 0x121 (ACK?) 5ms of silence DAQ sends 0x16B, 0x030, 0x000 Card responds 0x121 (ACK?) 8ms of silence DAQ sends 0x1BB, 0x000, 0x000, 0x000, 0x010 170ms of silence DAQ sends 0x10B Card responds 0x121 --- End code --- The card knows which slot it's in via the backplace connector pins A6, A7 A8. EDIT: Perhaps I should add that I am probing at the plugin, not at the backplane or logic board - I should probably change that so that one can probe the system when multiple cards are fitted. |
| H.O:
Service guide does say 187500 9N1 so that's verified. It also says that the 9 bits consists of; a start bit, 8 data bits, an attention bit and a stop bit. The attention bit is 1 if the 8 databits are an address/command, or 0 if the 8 data bits modify or provide data for the previously sent command. I moved the probing from the module itself to the backplane connector. Now the SRQ doesn't do that short pulse that was seen before. When a slot is polled by the 0x119, 0x11A, 0x11B commands the card in the respective slot responds with it's ID where 0x101-0x108 is 34901-34908 respectively. I've verified this with 34901, 2, 3, 5 and 7. |
| voltsandjolts:
Wow, thanks H.O!...you work much faster than me ;D This is a great start. --- Quote ---9 bits consists of; a start bit, 8 data bits, an attention bit and a stop bit. The attention bit is 1 if the 8 databits are an address/command, or 0 if the 8 data bits modify or provide data for the previously sent command. --- End quote --- Well spotted, I got the baud setting from the manual but missed the explanation of the 9th bit. |
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