Author Topic: Agilent probe interface ( AutoProbe and Probe Id)  (Read 12579 times)

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Offline tnt

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Agilent probe interface ( AutoProbe and Probe Id)
« on: April 20, 2011, 12:19:36 pm »
Hi,

I'm trying to find informations about the way the Agilent AutoProbe interface works.

The only bit of info I found was www.alciom.com/en/download/powerprobereadme.pdf
It has good info, but not much about the probe identification. It's more power oriented.

Quote
The Autoprobe pinout is described in the documentation, from left to right when looking at the
scope front panel :
pin 1 : +3V to +6V, depending on Rs
pin 2 : -3V to -6V, depending on Rs
pin 3 : Offset adjustment (-1mA to +1mA, voltage limited to +/-6V)
pin 4, 5, 6 : digital and analog probe recongition interfaces
pin 7 : Rs, the probe connects this pin to GND through a resistor Rs
pin 8 : -12V
pin 9 : +12V

What I gathered about the identification is that:

pin 5 (center pin and the outer ring) is an analog probe ID. The probe connect this to the ground through a resistor.
pin 4,6 are probably an I2C bus. They're pulled up internally and the X-series fw has reference to I2C bus for probe identification. But I have no probe using it.

The pin 5 is at the center of a voltage divider inside the scope between 5V and the GND. The scope has a 28.7k and 178k resistors internally, giving an idle voltage of 4.3V. When the resistor in the probe is connected in // with the 178k, the voltage drops.

The probe I have have these resistors (measured between the 'outer' pin ring and the BNC ground).
* N2890A - 11k
* 1152A - 56.4k

Does anyone know (or can measure) values for other probes ?
Does anyone know more details ?

 

Offline tnt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #1 on: April 21, 2011, 06:28:34 pm »
Come on anybody ? Anyone with even passive probes shipped by default with the 2000-X / 3000-X can at least measure the resistance of their probe (or the resulting voltage on pin 5 with the scope itself).

In the meantime, I digged in the firmware and I think 46.4k is the resistor value that indicate a 'Smart Probe' with I2C interface ... I don't have that value (or any combination to make it easily enough) so I'll have to wait to confirm this.
 

Offline Rufus

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #2 on: April 22, 2011, 03:01:44 am »
Not sure what you think anyone can do to help.

The ID pin to ground on tek and HP 10:1 passive probes I have is 11k. I think anything less is still considered to indicate a 10:1 passive probe.

Out of interest I stuck a 100k variable resistor between ground and the ID ring and the scope detected all kinds of 'unnamed' passive probes with 5:1 to 1000:1 attenuation and 50 ohm output or not. The only 'named' probes I saw were E2621, E2622, 1147, and N2790A.

Between 2.8 and 2.9 volts on the ring gave unsupported probe error messages, presumably because it expected and didn't find an I2C interface. I don't know what happens above 3.4v the 100k resistor didn't go that far.


 

Offline tnt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #3 on: April 22, 2011, 04:10:15 am »
Not sure what you think anyone can do to help.

Well, exactly what you did :p

The ID pin to ground on tek and HP 10:1 passive probes I have is 11k. I think anything less is still considered to indicate a 10:1 passive probe.

Out of interest I stuck a 100k variable resistor between ground and the ID ring and the scope detected all kinds of 'unnamed' passive probes with 5:1 to 1000:1 attenuation and 50 ohm output or not. The only 'named' probes I saw were E2621, E2622, 1147, and N2790A.

This is the list I extracted last night :

Code: [Select]
R       ID      Name

1000M   0x00    ?
1k      0x01    ?
3.16k   0x02    ?
9.09k   0x03    ?
14.7k   0x04    ?
19.6k   0x05    ?
21.5k   0x06    ?
28.7k   0x07    ?
31.6k   0x08    ?
61.9k   0x09    ?
34.8k   0x0a    ?
38.3k   0x0b    ?
42.2k   0x0c    ?
0k      0x0d    ?
11k     0x0e    ?
2.2k    0x0f    ?
6.2k    0x10    ?
1.5k    0x11    ?
46.4k   0x12    ?               (smart probe)
51.1k   0x13    1153   
56.2k   0x14    1152A
68.1k   0x15    E2621
75k     0x16    E2622
82.5k   0x17    1147
90.9k   0x18    E2697A
100k    0x19    N2790A
128k    0x28
121k    0x29    ADAPTER

As you said the unnamed ones are probably 'generic' values shared between several passive probes.


Between 2.8 and 2.9 volts on the ring gave unsupported probe error messages, presumably because it expected and didn't find an I2C interface. I don't know what happens above 3.4v the 100k resistor didn't go that far.

Interestingly it seems 1153, 1152A and E2697A are in the values and you didn't "see" them.
Even tough (at least for 1152A), there is definitely no I2C interface (I have such a probe).

Also, I tried putting a 46.4k resistor my self (I tried my best to get the value right using a bunch of resistors ... 10 of them :p) and got unsupported probe. But when I probed the pin 4 and 6 while plugging the resistor, I failed to see anything indicating the scope was trying to communicate in I2C ...




 

Offline Rufus

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #4 on: April 22, 2011, 04:54:17 am »
Interestingly it seems 1153, 1152A and E2697A are in the values and you didn't "see" them.
Even tough (at least for 1152A), there is definitely no I2C interface (I have such a probe).

This is what I scribbled measuring voltage on the ring, so I don't know what the thresholds are and I could have made mistakes:
Code: [Select]
0.8 100:1
1.4 10:1
1.7 10:1 50R
1.8 100:1
2.0 100:1 50R
2.1 100:1 50R
2.2 5:1 50R
2.3 5:1 50R
2.4 20:1 50R
2.5 50:1 50R
2.6 200:1 50R
2.7 1000:1
2.8 unsupported probe
2.9 unsupported probe
3.0 20:1
3.1 E2621 5:1 50R
3.2 E2622 5:1 50R
3.3 1147 100V/A 10:1
3.4 N2790A 50:1

Maybe I missed some in-between ones because you have to remove and re-apply the resistance for the scope to examine the probe again.  

56k // 270k is 46k4, maybe it is recognising a 1152A and just saying it isn't supported without naming it.

That powerprobereadme.pdf you linked seems to have gone or the link is bad.
 

Offline tnt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #5 on: April 22, 2011, 06:28:16 am »
* Great thanks for the measurements. I'll try to correlate those to the other values in the probe info structure

* Argh ... yes the document is gone ... and I didn't save a copy !
   Well, what's mostly missing is the values for Rs (to select a voltage between 3 and 6V ...)  I think it was between open and 40k but I'm not really sure anymore :(
 

Offline tnt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #6 on: May 01, 2011, 03:10:02 pm »
Well some more work on this, I found out several things.

The Agilent 3000-X autoprobe interface is a cost optimized version that doesn't have all the feature of autoprobe. What's missing mostly is the variable supply dual rail. Instead of providing 3 to 6V, it's providing a fixed +/- 5V which is not good for some probes among which the 1152A I have which wants +4V (it doesn't use the -4V rail).

Also it's indeed an I2C interface (pin 4 = SDA and pin 6 = SCL) to which a 24C02 is wired at base address 0xA2. The scope just reads the full 256 bytes when the probe is plugged.

I will next attempt to mod my 1152A probe by :
* Adding a 5V -> 4V LDO
* Replace the 56.4k ID resistor with a 46.4k one (indicating smart probe)
* Replace the 40k Rs resistor with a 10k one (indicating 5V supply)
* Add a 24C02 I2C eeprom filled with the dump of a 1158A probe
 

Offline kleptophobiac

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #7 on: September 04, 2014, 05:50:16 pm »
I know this is a tremendously old post, but I figured I'd add some more probe measurements.

N2893A
Pin 5 to GND resistance is 46.4k
Pin 7 to GND (Rs) resistance is 10k

N2819A
Pin 5 to GND resistance is 46.4k
Pin 7 to GND (Rs) resistance is 9.09k

I'll see about reading out the EEPROMs soon, as well as getting measurements on another probe. My goal is to get my N2819A to work with an MSO7104B - it's shameful that Agilent / Keysight won't update the firmware on the 6000/7000 series scopes to identify some (obviously hardware-compatible) probes.
 

Offline joris

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #8 on: February 01, 2015, 01:47:32 pm »
Hmmmm it'd be very interesting to use this to connect a uCurrent.
It could automatically set the right units and provide power.
Adding isolation would be even more awesome!

Hope someone can do it, otherwise I'll ad this to my "if I ever get fired and have to much free time" todo-list.

Does anyone have ideas on cheap donors to get the autoprobe connector from?
The N2744A seemed like a good candidate, but of course it is 400 EUR, go Agilent :)
 

Offline Jay_Diddy_B

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #9 on: February 21, 2015, 04:08:24 pm »
Hi,
I know this is an old thread but I found some really good information in the Patent (attached).
You might as well get the information from Agilent.

I had to zip the pdf to get it under the 1000KB limit.

Jay_Diddy_B
 

Offline abulafia

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #10 on: June 11, 2016, 12:15:56 pm »
I think TNT's link just moved to this one:
http://www.alciom.com/images/stories/downloads/powerprobe%201a.pdf

Interesting!
 

Offline ogoun

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #11 on: March 05, 2017, 06:56:34 am »
Greets all,
Thought I would resurrect this old topic rather than start a new one, as it seems relevant to this thread.

I have been looking at the connector module from a wrecked Agilent 1156A active probe.

The NV storage chip is an ST M24C02W, 2kbit (256 bytes) EEPROM.

Here is a text dump:


Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000  00 9B F6 01 A2 60 01 01 01 00 00 00 00 00 00 00  .›ö.¢`..........
00000010  00 00 4E B2 D0 5E 2B 61 2E 13 2B 61 2E 13 2B 61  ..N²Ð^+a..+a..+a
00000020  2E 13 47 C3 50 00 80 00 40 A0 00 00 00 00 00 00  ..GÃP.€.@ ......
00000030  BF C0 00 00 3F C0 00 00 38 D1 B7 17 41 20 00 00  ¿À..?À..8Ñ·.A ..
00000040  00 00 00 00 3F 00 00 00 3F 80 00 00 2F 80 17 D6  ....?...?€../€.Ö
00000050  00 00 0C 00 00 00 00 3F 35 C2 8F 31 B4 63 7D 00  .......?5Â.1´c}.
00000060  41 67 69 6C 65 6E 74 20 54 65 63 68 6E 6F 6C 6F  Agilent Technolo
00000070  67 69 65 73 00 30 30 00 00 31 31 35 36 41 00 00  gies.00..1156A..
00000080  65 6E 74 20 54 65 63 68 6E 6F 55 53 34 31 30 xx  ent TechnoUS410x
00000090  xx xx xx xx 00 00 00 00 00 00 00 00 00 00 00 00  xxxx............
000000A0  00 00 00 00 00 00 50 72 6F 62 65 20 53 79 73 74  ......Probe Syst
000000B0  65 6D 00 00 00 00 00 00 00 00 00 00 00 00 00 00  em..............
000000C0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
000000D0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
000000E0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
000000F0  00 00 00 53 6D 61 72 74 20 50 72 6F 62 65 00 00  ...Smart Probe..


There appears to have been some overwrite happening at address 0x80, but I assure you, the read is good (verified on 2 different device readers).

Maybe someone can analyse the less obvious parts of the data, to determine what is stored here, and what parts are read only, versus parts that are updated by the DSO...

From my own inspection..
The string at 0xF3 "Smart Probe" appears to be necessary for the probe to be recognised as valid.
The string at 0x8A is the probe serial number.
The string at 0x79 is the model number...
There is probably a CRC somewhere, but since the serial number has been munged, this will not likely work

Hope this is of use.

O
 

Offline Neganur

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #12 on: March 05, 2017, 01:25:35 pm »
I can help with some of it, I had a longer look at the contents of a corrupted 113x type probe.

Will post more once back in the lab on Monday.
 

Offline ogoun

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #13 on: March 05, 2017, 10:22:03 pm »
Hi Neganur,

Cool, it would be good to work out how the DSOX and MSOX cros treat the probe interface.. I am looking into making an adaptor for my hi res surface contact current probe, and it would be nice to have the CRO recognise that it was a current probe, and display current on the screen.
I also would like to connect my Tek ADA400A differential probe amp up to it as well, again taking advantage of the autoprobe interface to supply power and to configure the cro.

Also, maybe this thread should be in test equipment... Mods?

c ya,
o
 

Offline larry42

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #14 on: February 26, 2018, 07:10:59 am »
Does anyone know the approx. current required on the +12V and -12V lines for the Agilent diff. probes?
If you have an animated GIF in your avatar or signature then I reserve the right to think you're a dolt.
 

Online Wolfgang

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #15 on: November 07, 2018, 04:54:51 pm »
The maximum current cannot be more than 200mA, for the 12V and the downregulated voltage in total.
 

Online Wolfgang

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #16 on: November 20, 2018, 01:42:52 pm »
Hi,

I just completed a homebrew interface for AutoProbe I probes.

Details can be seen here:

https://electronicprojectsforfun.wordpress.com/using-the-keysight-autoprobe-interface-in-your-own-projects/
 
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Offline wkt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #17 on: November 21, 2018, 10:42:41 am »
Hi,

I just completed a homebrew interface for AutoProbe I probes.

Details can be seen here:

https://electronicprojectsforfun.wordpress.com/using-the-keysight-autoprobe-interface-in-your-own-projects/

This is really great reverse engineering. Also the 3D-printed complete connector is something that I was planning to do, can you share the files for recreating this? Thanks
 

Online Wolfgang

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #18 on: November 21, 2018, 01:01:15 pm »
Yeah, why not. I'm working on some improvements, then I'll put the STL in a downloadable file.
« Last Edit: November 22, 2018, 01:40:46 am by Wolfgang »
 
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Offline bson

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #19 on: November 22, 2018, 03:30:01 am »
 

Offline wkt

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #20 on: November 22, 2018, 11:07:27 am »
It would be great if you could share the PCB also along with a BOM, for example I have no idea of the pitch of those pogo pins row, and where to source the pins themselves.
My plan is to create a DIY HV differential probe, which will require some power, so instead of using batteries I would like to draw the power from that connector.
 

Offline Gribo

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #21 on: November 22, 2018, 11:54:54 am »
The probe pitch is 0.1". the pogo pins are standard round head 0.1" pogo pins. Shariar made a tear down of one of the Keysight probes. Keysight used a horizontal layout and socket, not vertical, like this one.
I am available for freelance work.
 

Online Wolfgang

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Re: Agilent probe interface ( AutoProbe and Probe Id)
« Reply #22 on: November 22, 2018, 12:01:58 pm »
Good video. Problem to reproduce is special parts, so I used standard stuff and a vertical layout. The Keysight spring mechanism is also nice, but needs a lot of mechanical parts to make it work. A simple clamp was easier to make and does the same.
 


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