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.pdfIt has good info, but not much about the probe identification. It's more power oriented.
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 ?