Comtech EF Data DMD20 - Manual (Page 21)

DMD20/DMD50/DMD2050/DMD2050E/DMD1050/OM20 Remote Protocol Remote Operations
MN-DMDREMOTEOP Revision 9 1–11
<FSN>: Frame sequence number ensures correct packet acknowledgment and data transfers (1
byte).
<OPCODE>: This byte identifies the message type associated with the information data. The
equipment processes the data according to the value in this field. Return error codes and
acknowledgment are also included in this field (2 bytes).
<...DATA...>: Information data. The number of data bytes in this field is indicated by the <BYTE
COUNT> value.
<CHECKSUM>: The modulo 256 sum of all preceding message bytes excluding the <SYNC>
character (1 byte).
The Modem RLLP is not software-compatible with the following previous
Radyne products: RCU5000 and DMD4500. These products may not occupy the
same bus while using this protocol as equipment malfunction and loss of data
may occur.
When transmitting a packet at 9600 baud, the Remote M&C should ensure that
the timeout value between characters does not exceed the time it takes to
transmit 200 characters (≈
 200 msec). If this timeout value is exceeded, the
equipment will timeout.
1.4
DMD20 Opcode Command Set:
The DMD20/DMD20 LBST Opcode Command Set is listed below: