Fluke 5500A locked out with RS232 setup

[Zermalmer]

Hi,
I am having a problem with our Fluke 5500A and haven't been able to find a way to operate it.

A colleague wanted to control the calibrator via RS232 for testing purposes (to write test procedures).
To do this, he changed the port setting from GPIB to RS232 in the setup menu.

Now, here is the problem: while the left side displays "0mV" and "Standby," there is no longer any display on the right side,
And the device only responds to button presses with a short beep.
If you hold down the "RESET" button while turning the unit on, the display shows "Reset Key held" as described in the manual,
But there is no corresponding output at the serial port. We were unable to establish communication (using a null-modem cable, 9600/8/N/1, host port) and could not get the calibrator back to a state where it could be operated normally.
Power cycling the unit did not help either. Up until this port change, the 5500A worked perfectly, and GPIB communication was trouble-free; we simply hadn't used the serial port before.
It is not being detected via the GPIB port either.

Is there a way to reset the calibrator (jumper, dip-switch, key compbination) so that it returns to normal operating mode?

To be honest, I’ve also got a request in with the Fluke service desk, but you know how it is... you try anything that saves time.

Greetings
Andreas

[ddrl46]

Does the righthand display still go through the usual steps like "loading waveforms" etc. when powering on?

When powering on the calibrator with the reset key held it should dump some stuff to to host port, but if that isn't working like you described it might be possible that one of the RS232 transceiver on the A9 board may be misbehaving.
Might also be worth trying a straight through rs232 cable just to make sure.

I'm not aware of a way to reset the calibrator without going through the front panel user interface unfortunately.

[Zermalmer]

Thanks for the answer.

I will try also a 1:1 serial cable, but I have no hope 

[Zermalmer]

I tried 1:1 cable, but without success. He remains silent.

[m k]

Table 5-1 of Operator Manual.

Button is a mechanical short.

Should there be an indication that soft keys have their function?

Maybe +/-12V is missing.

A9 has a JTAG, maybe its operation is simple enough.

[Zermalmer]

Afair the keys also respond like the others with short beep, or they didn't respond, because in the right section isn't anything displayed and no roujtine needs to check the keys

I’m also considering faulty voltage levels in the RS232 interface section.
And a missing routine to return to a possible jump to setup.

As mentioned, all works without any problem for over 25 years until the interface was switched to RS232  (whitch never been used afaik) :'(

However, my time (mainly) and expertise are too limited to dismantle the device and examine it myself.
That’s why I handed the device over to a professional, even though I would have liked to try fixing it myself.

[JoeMeta]

I'm using a very similar model - the Fluke 5520A.  It sounds like there's an issue with the firmware since the front panel controls are not responding.  However, sticking with theory that it is just a serial related issue, here are some things you can do to troubleshoot the serial connection and instrument state.

When in REMOTE mode the far right blue softkey must be pushed to bring it out of remote mode.
Use a crossover RS232 cable. I did up a custom RS232 cable for my implementation.  You have to ensure TX <--> RX and you aren't banging bits on the TX port of the device you're trying to talk to.
The serial cable needs to be connected to the correct port (not the one labeled To UUT)

There is a "Local Lock Out" command "LLO" / LOCKOUT that might have been sent to the calibrator.
See the programmer's manual: https://www.fluke.com/en-us/product/calibration-tools/electrical-calibration/electrical-calibrators/5500a#
Using RS232 to send "*RST" followed by "*CLS" then "LOCAL" might help.  You need to wait up to 6 seconds between commands.

Read that programmers guide very carefully, looks like it might be 7-bit ASCII, it is discarding the Most Significant bit.  (https://media.fluke.com/6cc212e7-e657-401a-a9e4-b10800be74c5_original%20file.pdf) adjust transmission settings appropriately.

[Zermalmer]

We couldn't get any output at all from the host port, regardless of whether we used a null-modem or a 1:1 cable.

And without communication there is no possibility to use commands