Look at the PIRA32 manual, section 15.3.6. An example of RT+ coding is given here.
Since the MicroRDS does not accept ASCII command UDG1=, the resulting command UDG1=301600004BD7,B00824A02005 valid for PIRA32 must be sent to the MicroRDS as an infinite loop like
1) Start - Control byte - 0x67 - 0x30 - 0x16 - 0x00 - 0x00 - 0x4B - 0xD7 - 0x01 - Stop
2) wait for 1 sec.
3) Start - Control byte - 0x67 - 0xB0 - 0x08 - 0x24 - 0xA0 - 0x20 - 0x05 - 0x01 - Stop
4) wait for 1 sec.
5) go to step 1
There are some recommendations related to the RT+ transmission published by 3rd party, I think you already know them, let me know otherwise, I'll provide that information via email.