So this Oscilloscope runs on Linux !
I didn't see an obvious serial boot output port. I probed the IDC connector and got nothing during boot.
ISL3243 RS-232 transceiver on the bottom side of the conga-SMX8X CPU module connected to the 6-pin connector on the CPU module.
You can buy a congatec 48000023 cab-RS232-Debug-ARM cable from Mouser.
Adapter cable for ARM console. MOLEX PicoBlade 6 circuit to two D-SUB 9 connectors.
Table 10 A35 and SCU Connector (X2) Pinout Description
Pin SoC Ball Description
1 SCU_GPIO0_01 SCU Debug: Transmit signal via ISL3243E RS-232 Transmitter/Receiver connected to UART4_TXD of the SoC
2 +VIN SMARC VDD_IN (+5 V)
3 GND Ground
4 UART2_TXD A35 Console: Transmit signal via ISL3243E RS-232 Transmitter/Receiver connected to UART2_TXD of the SoC
5 UART2_RXD A35 Console: Receive signal via ISL3243E RS-232 Transmitter/Receiver connected to UART2_RXD of the SoC
6 SCU_GPIO0_00 SCU Debug: Receive signal via ISL3243E RS-232 Transmitter/Receiver connected to UART4_RXD of the SoC
https://www.congatec.com/fileadmin/user_upload/Documents/Manual/SX8X.pdfAlso note that if only the outputs of the ISL3243E are probed without supplying valid RS-232 signal levels to any of the ISL3243E inputs, the ISL3243E may be in a low power mode with the outputs disabled.
The ISL3243E features an automatic powerdown function that
powers down the on-chip power supply and driver circuits. This
occurs when an attached peripheral device is shut off or the
RS-232 cable is removed, conserving system power
automatically without changes to the hardware or operating
system. It powers up again when a valid RS-232 voltage is
applied to any receiver input.
https://www.renesas.com/en/document/dst/isl3241e-isl3243e-datasheet