Comtech EF Data CDM-570 - Manual (Page 390)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Appendix E MN/CDM570L.IOM
E–4
E.4.3.1 Start Of Packet
Controller-to-Target: This is the character ‘<’ (ASCII code 60)
Target-to-Controller: This is the character ‘>’ (ASCII code 62)
Because this is used to provide a reliable indication of the start of packet, these two characters may not appear anywhere else within the
body of the message. For multi line text message, each line should end with a new line character ‘\n’. The carriage return & new line [\r\n]
combination should present only at the end of the message.
E.4.3.2 Target Address
Up to 9,999 devices can be uniquely addressed. Even though the any number of devices can be addressed, but they all should be
associated with single IP Address.
• For a CDM-570, address of ‘1’ is being used to address both modulator and demodulator.
• For CDD-564, each demodulator is identified by unique address from 1 to 4 respectively for all the four demodulators.
The address is not significant for commands Targeted system wide. But, it does has significance when associated with demod specific
commands like Frequency, Data Rate, etc.
The Controller sends a packet with the address of a Target - the destination of the packet. When the Target responds,
the address used is the same address, to indicate to the Controller the source of the packet. The Controller does not
have its own address.
E.4.3.3 Instruction Code
This is a three-character alphabetic sequence that identifies the subject of the message. Wherever possible, the instruction codes have been
chosen to have some significance. For example, TFQ stands for Transmit Frequency, RMD is for Receive Modulation type, etc.This aids
in the readability of the message, should it be displayed in its raw ASCII form. Only upper case alphabetic characters may be used (A-Z,
ASCII codes 65 - 90).