# 2. Safety

![Four ways to destroy the control board](https://docs.source-robotics.com/PAROL-docs/1.1/assets/board_warning.svg){ width="1000" }

!!! danger "Four ways to destroy the board"
    1. **A stepper driver module inserted the wrong way round.** Check the orientation against the DIAG pins
       before the first power-on ([Stepper drivers](https://docs.source-robotics.com/PAROL-docs/1.1/board/05-stepper-drivers/)).
    2. **A driver without its heatsink cemented on.** The TMC5160 modules need the heatsink and the fan.
    3. **An ST-Link connected with jumper wires without the programming adapter.** Use the adapter, or only
       the four pins named on [Firmware](https://docs.source-robotics.com/PAROL-docs/1.1/board/08-firmware/).
    4. **Reversed supply polarity.** The XT30 power input has no reverse-polarity protection.

- The board runs on 24 V, which is safe to touch; the power supply you connect it to is the mains device.
- The outputs switch up to 1 A at up to 48 V; the inputs take up to 50 V. The isolation between them and the
  robot holds only if you power them from an isolated supply ([Inputs, outputs and E-stop](https://docs.source-robotics.com/PAROL-docs/1.1/board/06-io-and-estop/)).
- The E-stop input is read by the firmware and acted on by the PC software; it does not cut the motor power
  ([Emergency stop](https://docs.source-robotics.com/PAROL-docs/1.1/02-safety/emergency-stop/) in the Robot Manual).
- With 3.3 V on the programming header the board turns on when the supply is connected and cannot be switched
  off with the button. Disconnect the 24 V supply before you connect the programmer.
- The drivers are hot after use; the fan must run whenever the motors are energised.
- Static electricity damages the microcontroller and the drivers. Unplug the supply and touch earthed metal
  before you handle the board or a driver module, and hold them by the edges.