Tektronix TDS540C GPIB issue when write protect disabled

[jhov]

I recently acquired a TDS540C and was going through the process of making backups of the NVRAM and FW and enabling options and ran into an issue I haven't seen before when trying to communicate with it via GPIB. I'm able to read the NVRAM and firmware using the unified tektool and when the write protect switch is on the GPIB interface works normally; but when the write protect switch is off the GPIB address is found at 29 and the instrument no longer responds to commands using PyVISA or NI MAX / NI Interactive Control. I have the address set to 1 and I've tried sending commands to 1 and 29 and neither work. I've also tried setting the 540C to address 29 and it still will not respond when the write protect switch is off.

Possibly related, before I realized the issue, I sent "PASSWORD PITBULL" and "WORDCONSTANT:ATPUT 327689, 1" to enable FFT. Without thinking I also sent "WORDCONSTANT:ATPUT 0x50006, 1", forgetting to convert it to decimal first. I haven't been able to find any documentation on these commands so I'm not sure if that just resulted in an error or if it wrote that value to address 50006 or something.

After realizing my error, I checked the error log and saw:


I'm running NI 488.2 v17.6 and NI VISA 18. I've done the same process without issue on my TDS540B so I'm at a loss here. Any ideas what could be the issue?

[jhov]

It's been a while since I've done this, but as I recall, the procedure I always followed was to boot it with the write protect switch off, but I just tried booting it with it on then turning it off after it was running and I was able to write settings to it as needed. Maybe my memory is failing me, but either way I was able to make back ups and enable options. It's still interesting that the unified tektool was able to read the memory when booted with the protection switch off, while nothing else could read or write to it in that state.