project: extending HP3478A functionality

[yo0]

It should respond to UART commands without any connections. Just the bare board.

I think yes it does. If I send text over serial monitor it appears in the console. I don't have experience with Arduino, sorry

I needed load a serial sketch to do that

It's good to know, that the UART works. But you'd get the response from the hp3478-ext firmware. Just to know that it's loaded and works.
It should respond with the <GPIB> prompt.

The connector pinout is standard. Just google "GPIB pinout". You'd find the pictures of the connector with the pin names and numbers.

unfortunately didn't work, i check the wiring and pinout, change the arduino for another (both new) and nothing, seems like the software is not running.

what software do you use for sending requests to the arduino?

best regards.


Pio

[kirill_ka]

what software do you use for sending requests to the arduino?

kermit
Using the following settings:
open port /dev/ttyUSB0
set flow-control none
set carrier-watch off
set speed 115200
set terminal lf-display crlf
connect

I don't think that incorrect settings in the eeprom is an issue here. But I recommend also programming the eeprom (eep file) to be sure.
And please, disconnect the gpib connector. First we need to know that the serial communication is working.

[yo0]

what software do you use for sending requests to the arduino?

kermit
Using the following settings:
open port /dev/ttyUSB0
set flow-control none
set carrier-watch off
set speed 115200
set terminal lf-display crlf
connect

I don't think that incorrect settings in the eeprom is an issue here. But I recommend also programming the eeprom (eep file) to be sure.
And please, disconnect the gpib connector. First we need to know that the serial communication is working.

thank you, I think the software is running

++addr
++ver

So I think the wiring is the culprit or perhaps me

now i need figure out where is the mistake.


Pio

[kirill_ka]

thank you, I think the software is running

Keep on trying! Eventually it will work
The next task is to get a reading from the 3478 through the serial.
Try ++read

[yo0]

thank you, I think the software is running

Keep on trying! Eventually it will work
The next task is to get a reading from the 3478 through the serial.
Try ++read

thank you!  it reads!

so what's next?

best regards



Pio

[kirill_ka]

thank you!  it reads!

so what's next?

Then it just works. To enable the extended functions of the 3478, enter OX1w command (before entering any of the ++ commands).
This is also can be done by flashing the eeprom (eep file).
Then you should see "init ok" after OX1 or during the start up.
All the functions are initialted with the SRQ key. Also enable "power on SRQ" with the dip switch on the back of 3478. It allows the firmware to know when the 3478 is initialized.

Some of the steps above are mentioned in the hp3478 ext documentation. But it's outdated, I know...

[yo0]

Thank you, now it works, just something strange occurs after the self test ok , two different screens, one with the power on sqr switch and other without it active.

Maybe 250ms delay isn't enough.

Any ideas?

best regards.

Pio

[kirill_ka]

Thank you, now it works, just something strange occurs after the self test ok , two different screens, one with the power on sqr switch and other without it active.

Maybe 250ms delay isn't enough.

Any ideas?

best regards.

Pio

Do you power the arduino board externally?
If yes, then those errors are probably normal. The 250ms delay only counts if the atmega and the 3478 are started simultaneously.
Please, monitor the error codes for some time and tell me if something different appears. If they only happen during the start up, I can disable them.
Are the "power on srq" and "no power on srq" errors consistently different?

[kirill_ka]

Pio, It's a bit strange, that you are getting E:2F000005 and E:30000003
Those codes are not happening on the first attempt to send something to the 3478.
So there's a slight chance that the errors indicate some of the GPIB control lines are not wired up correctly.

[yo0]

Thank you, now it works, just something strange occurs after the self test ok , two different screens, one with the power on sqr switch and other without it active.

Maybe 250ms delay isn't enough.

Any ideas?

best regards.

Pio

Do you power the arduino board externally?
If yes, then those errors are probably normal. The 250ms delay only counts if the atmega and the 3478 are started simultaneously.
Please, monitor the error codes for some time and tell me if something different appears. If they only happen during the start up, I can disable them.
Are the "power on srq" and "no power on srq" errors consistently different?

yes i power it externally, if i power up the multimeter first got no error messages, the error codes stay the same for both srq switch states. E:30000003 for off and E:2F000005 for on,  every time got the same code, i  keep the power on srq switch to on as your advice. i am evaluating if it keep external attached or internal (have hard time soldering to ic sockets). can disable the displayed error codes via commands at the terminal?


best regards and thank you again for your valuable help and kindness.

Pio

[yo0]

Pio, It's a bit strange, that you are getting E:2F000005 and E:30000003
Those codes are not happening on the first attempt to send something to the 3478.
So there's a slight chance that the errors indicate some of the GPIB control lines are not wired up correctly.

i recheck the wiring and it match your table.

Pio

[kirill_ka]

can disable the displayed error codes via commands at the terminal?

Please, try the attached version. I've added the option.
Oerr_disp0w should disable the on-screen codes.
Disclaimer: I've not tried it yet myself

[yo0]

thank you, it works!, now if i turn off the dmm the terminal connected to the arduino show errors, but i think it is normal.


best regards

Pio

[Miti]

As someone may have noted The hp3478ext has a temperature measurement function.
It only supports 1kOhm 3850 ppm/K RTDs. The constants for which are hardcoded.
Yesterday I found a source of cheap sensors: https://aliexpress.com/item/32872179878.html
They look similar to the Honeywell sensor (700-102BAB-B00) that I have.

Hi Kirill,

How do you access that function? I think that I asked and I think that you answered, so forgive me if I'm too lazy to look through all the posts but did you publish a complete, updated menu tree anywhere. I know there is one in reply#19 but I think is obsolete by now.

Cheers,
Miti

[kirill_ka]

Hi Miti,

It shows up as TEMP when you cycle through with SRQ key in OHMS mode.
But it's hidden when there's nothing connected.

[Miti]

Aha, I found it, it didn't show up with the input open. However, it is not dynamic for me, it only reads the temperature once when i select the function and doesn't change when I change the resistance. I don't have an RTD, I simulated it with 100Ohm and 82Ohm.

[kirill_ka]

Aha, I found it, it didn't show up with the input open. However, it is not dynamic for me, it only reads the temperature once when i select the function and doesn't change when I change the resistance. I don't have an RTD, I simulated it with 100Ohm and 82Ohm.

It only has 1K RTD constants compiled in. So I'd try 1000 and 820 instead
I use 1k because it's more suitable for 2 wire measurements.

[Miti]

Aha, I found it, it didn't show up with the input open. However, it is not dynamic for me, it only reads the temperature once when i select the function and doesn't change when I change the resistance. I don't have an RTD, I simulated it with 100Ohm and 82Ohm.

It only has 1K RTD constants compiled in. So I'd try 1000 and 820 instead
I use 1k because it's more suitable for 2 wire measurements.

And that’s exactly what I used, 1k and 820Ohm but… brain fart.

[kirill_ka]

However, it is not dynamic for me, it only reads the temperature once when i select the function and doesn't change when I change the resistance.

Which revision are you using by the way?
It just came up to me that there was a bug fixed in rev2.1.

Recently I checked accuracy with a body thermometer. The readings were rather close (~0.2K difference). I think it's ok as I'm just using generic RTD constants.

[Miti]

Which revision are you using by the way?
It just came up to me that there was a bug fixed in rev2.1.

Recently I checked accuracy with a body thermometer. The readings were rather close (~0.2K difference). I think it's ok as I'm just using generic RTD constants.

I was behind with the updates. I don't know what revision was because it wasn't showing at ++ver but definitely was one with the bug. I updated to 2.2 and it works now.

Thanks Kirill!

[Miti]

Kirill,

I'm trying your extension with this software:
https://www.eevblog.com/forum/testgear/hp-34401a-standalone-software

For some reason I can't make it work. Do you know why? Have you tried this SW?

[kirill_ka]

For some reason I can't make it work. Do you know why? Have you tried this SW?

Hi Miti,

I'll take a look. Maybe it's using some of the ++ commands which are not implemented in hp3478ext.
Thanks for the link, interesting software!
Corrected link: https://www.eevblog.com/forum/testgear/hp-34401a-standalone-software/

[kirill_ka]

Kirill,

I'm trying your extension with this software:
https://www.eevblog.com/forum/testgear/hp-34401a-standalone-software

For some reason I can't make it work. Do you know why? Have you tried this SW?

The first issue was <LF> line termination. Now the hp3478ext supports <CR>, <LF> and <CR><LF>.
The second issue caused by the "software" continuously issuing ++read command. And the hp3478ext did not support command interruption which caused loss of any other commands.
Fixed in https://github.com/KIrill-ka/hp3478ext/releases/tag/r2.3
Now it works ok, besides that the first connection attempt fails (unless command echo is disabled with OI0w).
Second attempt should work even if echo is enabled.

[kirill_ka]

Note that "hp-34401a-standalone-software" seems to have some serious issues with the way how it updates the readings.
1. It doesn't check the actual status of HP3478A. It just sends the range switch command without checking the result.
2. The displayed range is updated immediately while it still displays previous readings.
3. In my setup it seriously lags behind the HP3478A. For example, if I switch from V to  , it displays past V readings as Ohms for a good few seconds.

Maybe my 12 year old core i5 CPU is not fast enough to keep up with 40 year old MCU of the HP3478A?

[Miti]

Thanks Kirill, it works now but I see those issues as well and my laptop is I7  .
If I set it to fast, beside lagging behind the instrument, I see something that looks like burst reading. It updates fast a number of times and then it freezes for half a second or so. This happens with AR488 as well.