User's Manual

45
Control Protocols
The following section describes the control protocol employed on the
RS232 link for controlling the SOLO transmitters and receiver
equipment.
Connection details are detailed in previous sections.
Note that only features that are licensed for use in the SOLO units can be controlled. The protocols
listed here cover all possible features. Attempting to activate an unlicensed feature will simply result
in the command being ignored by the SOLO unit.
1.1 RS232 Control – General Principles
The physical interface is RS232 but this can be converted to RS 485
with an external adapter where multiple units are controlled over one RS
485 bus.
Normal operation involves sending a packet from the control device
(normally a PC) to the device being controlled. If the packet satisfies an
address integrity check, then the controlled device will action the
command and send a reply.
For compatibility with modems an ASCII style protocol is used.
Ports are set for 8 bits, No parity, 1 stop
1.2 Packet Structure Sending (from PC)
ASCII Value
STX 02h Start byte
0-9 30h-39h 4 byte unit address. In range 0-9999
R 20h-7Eh 1 byte command type. r read, w write or
m misc
I 20h-7E 1 byte indicator of internal data block
ABC 20h-7Eh Command –three byte mnemonic
; 3Bh Separator
PQR 20h-7Eh Data –Optional, variable length
; 3Bh Separator
X 20h-7Eh Sum Check
ETX 03h End byte