Comtech EF Data DMD20 - Manual (Page 18)

DMD20/DMD50/DMD2050/DMD2050E/DMD1050/OM20 Remote Protocol Remote Operations
MN-DMDREMOTEOP Revision 9 1–8
RCU-340 1:1 Switch 03
RCS-780 1:N Switch 04
RMUX-340 Cross-Connect Multiplexer 05
CDS-780 Clock Distribution System 06
SOM-340 Second Order Multiplexer 07
DMD-4500/5000 Modulator Section 08
DMD-4500/5000 Demodulator Section 09
RCU-5000 M:N Switch 10
DMD20 Modulator 20
DMD20 Demodulator 21
DMD20 Modem 22
DVB3030 Video Modulator, DM240 23
RCS20 M:N Switch 24
RCS10 M:N Switch 25
RCS11 1:1 Switch 26
Reserved for future equipment types 27-31
Multi-drop override IDs 01 or 02 can be used interchangeably to broadcast a
message to a DMD-3000/4000 Modem, DMD-4500/5000, or a DMD20 Modem.
Radyne recommends that the multi-drop override IDs be issued only during
system configuration as a bus test tool by experienced programmers and that
they not be included in run-time software. It is also advantageous to consider
the use of multiple bus systems where warranted by a moderate to large
equipment complement.
Therefore, if a DMD20 Modulator is queried for its equipment type identifier, it will return a "20"
and DMD20 Demodulator will return a "21". A DMD20 Modem will also return a "22".
1.2.6 Software
Compatibility:
The COMMSPEC, operating in conjunction within the RLLP shell, provides for full forward and
backward software compatibility independent of the software version in use. New features are
appended to the end of the DATA field without OPCODE changes. Older software simply
discards the data as extraneous information without functional impairment for backward
compatibility.
If new device-resident or M&C software receives a message related to an old software version,
new information and processes are not damaged or affected by the omission of data.
The implementation of forward and backward software compatibility often, but not always,
requires the addition of new Opcodes. Each new function requires a new Opcode assignment if
forward and backward compatibility cannot be attained by other means.
When Radyne equipment is queried for bulk information (Query Mod, Query Demod, etc.) it
responds by sending back two blocks of data; a Non-Volatile Section (parameters that can be
modified by the user) and a Volatile Section (status information). It also returns a count value that
indicates the size of the Non-Volatile Section. This count is used by M&C developers to index
into the start of the Volatile Section.
When new features are added to Radyne equipment, the control parameters are appended to
the end of the Non-Volatile Section, and status of the features, if any, are added at the end of the