User Modes
V1 firmware uses access modes to decide whether a command is allowed to modify a setting.
The current mode is read or changed with usrmode.
Access modes are not a replacement for hardware protections, current limits, interlocks or safe operating procedures. They are a firmware-level guard against accidental use of commands that should not be available in every context.
Modes
The public firmware documentation uses these modes:
0: restricted.1: normal.2: advanced.
The default user mode is 2.
Products may load a saved mode at startup. Invalid saved mode values are restored as 2.
Read the current mode
>> usrmode
2
Change mode
The write form is:
>> usrmode 1 <key>
1
>> usrmode 2 <key>
2
The key must authorize the requested mode. If the key is invalid or insufficient, the firmware sets an invalid-argument error and leaves the mode unchanged.
Startup behavior
The UART configuration stores the user mode together with baud rate, board ID, multiplexing, error mask and sequencer enable state.
At startup, restricted, normal and advanced modes may be restored. Invalid values are replaced by the default mode 2.
Common write restrictions
The exact restrictions are implemented by each command. Common patterns are:
- Read-only commands such as
version,IDN?,serial,err,errlistand many monitoring commands can be read without changing mode. - Normal access is required for common user writes such as
userdata write,errmsk,errclrand many product setpoints. - Advanced access is required for communication and integration features such as
brate,bdid,muxon,memw,sequwrites andregswrites.
Failure behavior
When a command is not allowed in the current mode, it usually sets CMD_INVALID_ARG and returns the current value or no value depending on the command.
Use err after a failed write to confirm the error state, then errclr after correcting the command.
Practical recommendation
For normal scripts:
- Do not change
usrmodeunless you need to. - Use the default mode
2during controlled laboratory setup. - Use normal or restricted mode for deployed systems where accidental advanced writes should be avoided.
- Never depend on user modes as the only safety layer.

