I haven't been working with the Arduino MEGA 2560 for very long and unfortunately can't get any further at the moment.
I have to switch 24V four times with the Arduino. Alternatively I could imagine to amplify the voltage of the digital output with an op-amp.
Just with a transistor? But because the UMS00025.20T (which is NOT a relay) needs positive voltages you might can get away with simple pull ups on the line. But if they really need 6mA that will need big resistors.
Alternatively you can use optocouplers as high side drivers.
But why on earth didn't you get the UMS00025.20T05???
Kimso:
The problem is the price of an USMS00025... I've only asked for a cheaper solution.
A MOSFET that can switch a 24v load with a <5v signal is under US$1. It's cheap.
You haven't really explained what you are doing and why. We don't have a schematic, we don't have a lot of information. As a result, I don't think you are getting the answers you likely envisioned.
Thing is, he needs a high side driver. Yes, can be done with transistors as well. But as he only needs max 6mA I think an opto is an easy and cheap solution.