User's Manual

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5.
Interface
specification
The asynchronous serial interface on the RIM 902M operates at 3.0V. It is
similar to RS-232 except that 0V represents a “low” and 3V represents a
“high.” This interface can be connected directly to a micro-controller, or
through a UART to a microprocessor data bus.
MASC and RAP link-layer protocols
The RIM 902M requires a serial link-layer protocol to carry data, radio control
instructions, and radio status information between the RIM 902M radio modem
and the computing device to which it is attached. Two protocols are supported:
Mobitex Asynchronous Communication (MASC) and Radio Access Protocol
(RAP).
If you are using a MASC application with another Mobitex radio and are now
migrating to the RIM 902M, you do not need to rewrite the application in RAP
– simply continue using the MASC application. If you are writing a new
application for the RIM 902M, you will need to choose whether to use MASC
or RAP as your link-layer protocol.
MASC assumes a high-noise environment where bit errors are likely to occur
on the serial link between the radio modem and the computing device. MASC