Hi Fraros,

the tag doesn't need to be initialized, but the reader itself does (after every power up and error). After shipment all fields on the tag are pre-initialized with the value 16#0 except for the UID (unique identifier) field.

Before reading or writing a tag you need to reset the reader (also known as INIT command).

Before the reader has been initialized it's LED is blinking green. After the reset command the LED should be steadily shining green, which means it is ready for operation.

What kind of software are you using for commissioning the reader?

You should just ignore the INIT command. All it does is to fill up the tag storage with a predefined byte value.

Your MDS D421 is a 2000 byte FRAM transponder. It's user address space is from address 0 (0000) to 1999 (07CF) = 2000 byte.

If reading or writing still isn't working you should submit the telegrams you send to the reader.