How can I make a probe that attaches to the AutoProbe interface and gets properly detected (beyond simple resistor programming) ?
Is there a way to provide probe info for the S-Series scopes so that a homemade probe can be recognized by serial number and cal data ?
Details here:
Using the Keysight AutoProbe Interface in Your Own Projects – Electronic Projects for Fun
Hi Al,
no good move in my opinion. This means that
- if Keysight does not have a probe for a your special purpose, you are out of luck.
- you cannot elegantly use a (special, homebrew, ...) probe that solves your problem because it will not be recognized.
The hardware in the probe seems to be some simple EEPROM. That should be makeable. The problem is the software/driver side, and this is no fun with undisclosed interfaces.
What can be done is to use the functionality of the standard probes as explained in the expired AutoProbe patent.
These have the most common termination impedances and division factors coded by resistors. For the two problems I had
- N7026A to N9000A CXA and E5071C and
- 200V tolerant low capacitance FET probe to S-Series
I used this type of solution and it works (see website). I still think an open interface would be a sales argument.
Regards
Wolfgang
Due to the number of probes that we DO have, and that are in development, and the technical support that would be necessary to support access to an API for probes, we have made a business decision to not support the ability of customer-designed probes to communicate with the scope.
We have provided access to MATLAB programmability. This provides the ability to create almost any transformation of input data to output display that you might need, including scaling, changing units, or frequency-domain correction.
If you have ideas for probes that we should add to our portfolio, you should talk to your local Sales Rep, Distributor, or Technical Call Center.
Al
Hi Al, thanks for your reply,
but unfortunately its no solution for the problems I ran into. Lets recapitulate:
The two measurement problems I have at the moment are:
- Attach a homemade AC FET Probe to an S-Series scope. Keysight have nice probes, but none has a 200V offset voltage and a high bandwidth of more than a GHz.
- Second, I wanted to attach a N7026A current probe to a N9000A CXA spectrum analyzer or VNA like a E5071C or E5061-3L5 for stability analysis.
You gave me the advice that I should adress my needs to Keysight representatives. This was the first step I took, and I got the reply that Keysight does not see a solution for any of those. The next step was to adress the issues in Keysight support forums. Again, I only got either negative or no answers how to do this. Just if interested, my instrument portfolio is listed in my EEVBlog profile (Wolfgang).
The current probe discussion can be seen here:
How can I attach a wideband current probe (e.g., N7026A) to my signal analyzer (N9000A CXA) ?
The FET Probe can be seen here:
High Frequency Probes – Electronic Projects for Fun
Instead of just living with the fact that nobody wants to provide a reasonable solution, I started researching the interface myself, and I found a (not perfect) perfect solution for both topics.
For the FET Probe, I used the resistor-coded probe identification possibility and found that a recognition as a 1:10 probe is possible and works.
The solution for the N7026 was more difficult, but works by emulating the AutoProbe environment for the probe and providing a 10M:50Ohm buffer. Such a buffer was once available by Keysight, but was discontinued some years ago and the old model is not supported by the current S-Series scope.
To convert my usable solutions to good solutions it would be elegant to exchange information like scaling factors, serial numbers and probe types and calibration stored in a probe EEPROM. The alternative you provided by using matlab or user tables to do this is possible, but very clumsy, to say the least.
In the old times (Motto: "HP - Invent") increasing solution value by a customer addition was welcome. Now, we are facing a more or less tight single-vendor strategy even where no solution is available.
Such a strategy is not a sales argument. I deferred the purchase of an E5061B-3L5, one of the major reasons being the problems above.
To answer your questions, both at once:
You can't. Besides adding HW in the probe to generate the necessary serial signals to send to the scope, you would have to modify the Scope App to use the data that was transmitted. We have chosen to not make that capability available outside of Keysight.
Al