This reproduces with SCPI over serial (USB CDC). During probe() the sdi->connection_id gets set to /dev/ttyUSB2, and "somewhere along the path" to sigrok-cli's config_get() call the value has changed to "/dev/ttyUSB2:115200/8n1". Which results in a conn= value that cannot be used for subsequent invocations. It's yet to get determined whether this is an issue in the library or in the application. I'd suspect the library since SCPI handling is concentrated there. How to reproduce: $ sigrok-cli -d scpi-dmm --scan $ sigrok-cli -d scpi-dmm --show with a UART adapter which is covered by auto-scan, or gets specified in the -d option. Have noticed this during GWInstek GDM-8xxx development. Source code eyeballing suggests that TCP could suffer from a similar issue, where colons get added to connection ID values.
For the record here is the output as generated by the config getter and after some common code executed after the probe routine. $ sigrok-cli --scan sr: scpi-dmm: DIAG: probe_device() conn text: '/dev/ttyUSB2' The following devices were found: sr: scpi-dmm: DIAG: config_get() conn text: '/dev/ttyUSB2:115200/8n1' scpi-dmm:conn=/dev/ttyUSB2:115200/8n1 - GWInstek GDM8341 1.04 with 1 channel: P1