Research Concepts RC2000C User Manual
Page 91
RC2000C Az/El Tracking Antenna Controller
Appendix E
Communications Protocol
83
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byte 3:
'F'
ASCII 'F', for offline.
byte 4:
ETX
byte 5:
'chksum'
the checksum. The checksum character is simply the bit-by-bit
exclusive OR of all characters in the message starting with the
STX character through the ETX character.
RC2000 UNRECOGNIZED COMMANDS - NAK REPLY
If an unrecognized command arrives (one whose command code is either unknown or whose length is
not compatible with the given command code, but which has the correct address and checksum), a
NAK reply is sent to the host. The format of the NAK reply is ...
byte 0:
NAK
byte 1:
A
where A is the RC2000 address
byte 2:
'CC'
the command code of the unrecognized message.
byte 3:
ETX
byte 4:
checksum
DEVICE TYPE QUERY COMMAND
The SA Bus specifications require that command character 30h must trigger the return of the six-
character device type string. The message format for this query will be ...
byte 0:
STX
byte 1:
A
where A is the RC2000 address
byte 2:
30h
30 hex - the device type query command code
byte 3:
ETX
byte 4:
checksum
The reply to this query will consist of 11 bytes …
byte 0:
ACK
byte 1:
A
where A is the RC2000 address
byte 2:
30h
the device type query command code
bytes 3-6:
'XXXX'
where the value of 'XXXX' depends on the mount type.
'2KCA' for elevation over azimuth mounts,
'2KCP' for polar mounts with power declination adjust,
'2KCE' for azimuth over elevation type mounts.
bytes 7,8:
'XX'
where XX is the version number, for example if the current
software version number were 4.31, XX would be '43'.
byte 9:
ETX
byte 10:
checksum
DEVICE STATUS POLL COMMAND
The SA Bus specification requires that command character 31h cause a device to return its status
information. The reply to this command includes azimuth, elevation and polarization position, current
satellite name, as well as limit, alarm and drive status information. The status poll command message
consists of 5 bytes and the format is;
byte 0:
STX
byte 1:
A
where A is the RC2000 address
byte 2:
31h
the status poll query command code
byte 3:
ETX
byte 4:
checksum
The response to this command will consist of 38 bytes, which will be a combination of ASCII and binary
data fields. The binary data will be placed in the lower nibble of a byte whose higher nibble will be
initialized to a value that will make the result an ASCII character. The idea with this response is to be