TRIO Motion MC206X connection issues when wired up

I'm new to TRIO line of controllers, only used mitsubishi PLCs before.

I have this MC206X controller which refused to accept connection via USB while it was inside the machine. It was giving me "usb device descriptor failure" and didn't recognise the TRIO driver.

I took it out and back to the office, and it connects just fine now with only power input.

The unit is using Serial B port to a HMI, standard I/Os, analogue outputs and 3 servos connected. I suspected the other serial connection and unplugged it initially. Still couldn't connect.

I'm stumped. I can modify the program now, but i'd really like to plug in and monitor it while the machine is in operation.

Anyone with experience with TRIO controllers and monitoring mode?

In my experience, especially with win7+ the USB is temperamental at best.
I’ve always used serial since because of this.

Never worked out what it was, but gave up long ago

The strangest thing, I'm able to connect if I power up the TRIO controller without any peripherals attached and then connect the IOs and servos and HMI after PerfectMotion software is connected to the unit.

If it works, it works.
I quite like working with TRIO basic after all.