Frequently Asked Questions

Why do I have to CAL (calibrate) the P1125?  What is calibration doing?

• Calibration is applying known internal loads at each voltage in order to cancel out any offset in the (current) measurement paths. These offsets are generally small and independent of temperature.

• VOUT is also being calibrated.

Can the P1125 measure in-rush current?

• The P1125 employs a “soft start” feature which initially sets the output voltage to its lowest value, connects to the DUT by switching a relay, and then steps the voltage up in 100mV increments until the target voltage is reached.

• You can enable Hard Connect which bypasses the soft start algorithm. See Display/Other Controls

• You may have a downstream switch that connects the P1125 to your target device. Note that the P1125 will disconnect if the in-rush current exceeds ~3.2 Amps for >= ~5ms.

When I try to connect probe to the DUT, the P1125 reports a `ISOURCE2` error?

• If the DUT has a high in-rush current, that peak current may trip the P1125 maximum current safety threshold.

• Often this can be overcome by connecting again quickly. The in-rush may be reduced from the first connection, allowing a subsequent connection attempt to work.

How can I wipe WiFi networks and passwords from the P1125?

• Yes. Through the Admin menu.

Can I SSH or remote desktop into the P1125 Raspberry Pi?

• No, all user accounts are disabled, and there is no ssh service running.

Can the p1125 be scripted?

• Yes. It uses JSON-RPC. The JSON-RPC API documentation may be accessed via the Main menu.

• See https://github.com/sistemicorp/p1125_scripts.git

Can a local monitor, mouse, and keyboard to operate the P1125?

• No.

Do I have to Shutdown the P1125, or can I just remove power?

• You should always Shutdown, one of two ways, and remember to wait until the LED is OFF (stops blinking).

  • Press the OFF button on the side of the P1125

  • Menu->Shutdown

• Without shutting down you risk corrupting the SD Card.

Can a direct ethernet connection to PC be used?

• Yes.

• A crossover cable can be used to directly connect the P1125 to a PC over their wired ethernet ports.

• In order for this to work, the PC networking service needs to bridge the ethernet network. It is beyond this Help scope to detail the steps required. One may search the internet on how to directly connect a Raspberry Pi 4B in this way and find useful tips.