This Studer line out card, part number A949.0420, is a great addition for your D21m and D23m modular I/O system, offering 8-channel analog output functionality.

To use this Studer 8-channel analog line out card, first make sure your D21m or D23m modular I/O system is powered off. Then, carefully insert the card into the appropriate slot. After that, you can power on the system and start using it to output analog signals. When handling the card, be gentle to avoid any physical damage. For maintenance, keep it in a clean and dry environment. If you notice any issues, it's best to consult a professional technician.