Power limit warning can be overridden in serial coupling mode

[AndersWestman]

• Firmware version: 1.01
• Shield version: r5B12
• Powerboard version: r5B12

Expected behavior

Power limit warning are supposed to pretend settings over 310W.

Actual behavior

In serial coupling mode power limit warning can be overridden if the PSU is in cc-mode and the load is small, below about 10 ohm, or shorted output.

How to reproduce

Coupling: Serial
Volt: 80V
Load: 0-10 Ohm (shorted output works fine to reproduce this)

Enable output and increase the current in cc-mode.
At 3.876A power limit warning will occur, as expected.
In step-mode or by rotary encoder it is however possible to go all the way up to 5A (400W) if it’s done with about max one step per second.

[prasimix]

Additionally, when load is disconnected it is not possibly to change output values due to Power limit exceeded error.

[AndersWestman]

More observersions, setup as described above.

Load 0-4.7 Ohm.
Keypad or SCPI-command can be used to go back under power limit level with no load or output off.

Current can be set from about 1.5-3A to anything up to 5A using keypad or SCPI-command without power limit warning.
If current is set to something below 1-1.5A power limit warning occur as expected. This limit does not seem to be fixed. Sometimes I was able to jump directly from 1.1A to 5A without any warning, but sometimes I have to go from something like 2-3A. From 3A to 5A seems to always work.

With a 10 ohm load the PSU shut down due to “CH2 fault detected” then jumping from 3A to 5A using keypad.

**ERROR: -243,"CH2 fault detected"
**ERROR: -350,"Queue overflow"
**ERROR: -243,"CH2 fault detected"
**ERROR: -350,"Queue overflow"
**ERROR: -243,"CH2 fault detected"

[prasimix]

Fixed