Identifier, read/write, for assigning an address to the Pluto it is connected to. Each Pluto connected to the Pluto safety bus needs an IDFIX. The IDFIX number is programmable, i.e. the user can choose the number. Suitable for Pluto A20 v2, Pluto B20 v2, Pluto B22, Pluto B46 v2, Pluto D20, Pluto D20 (Harsh Env), Pluto D45, Pluto D45 (Harsh Env), Pluto O2, Pluto S20 v2, Pluto S46 v2.