The 'plug in signal' is the signal that causes the car to beep when you plug in a charging lead. The charger detects PP connection, then sends a pulse on that line. You don't need to do anything with this line, it's unidirectional
EV activation request likewise sends a signal to the VCM when a valid CP signal is detected, so the VCM can wake up the relevant parts of the EV drivetrain to start charging. The VCM controls the battery relays for instance. This is something you can use as an input to your controller to know when it's safe to engage the battery to the charger.
It shouldn't be hard at all to get the OBC from gen1 to work. Synthesize the battery and VCM CAN messages (I'd expect you need at least: 0x1DB, 0x1DC, 0x55B, 0x5BC, 0x50B, 0x1F2) and otherwise just hard-connect a charging port and power to the OBC. I think you can get away with not even using any relays, just connect a 400V battery directly to the charger. It is a very simple bit of kit internally, I've played with it a bit and it seems to not care at all about the majority of CAN messages, even if you mangle everything but the important bits.
EV activation request likewise sends a signal to the VCM when a valid CP signal is detected, so the VCM can wake up the relevant parts of the EV drivetrain to start charging. The VCM controls the battery relays for instance. This is something you can use as an input to your controller to know when it's safe to engage the battery to the charger.
It shouldn't be hard at all to get the OBC from gen1 to work. Synthesize the battery and VCM CAN messages (I'd expect you need at least: 0x1DB, 0x1DC, 0x55B, 0x5BC, 0x50B, 0x1F2) and otherwise just hard-connect a charging port and power to the OBC. I think you can get away with not even using any relays, just connect a 400V battery directly to the charger. It is a very simple bit of kit internally, I've played with it a bit and it seems to not care at all about the majority of CAN messages, even if you mangle everything but the important bits.