Dawn CONTROL-1500A Manual page 80

CONTROL-1500B Single Axis Antenna Controller
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:
byte 1:
byte 2:
byte 3:
byte 4:
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 able to reproduce the information presented on the LCD to the user
when manual mode is active. The format of the response will be;
byte 0:
byte 1:
byte 2:
bytes 3-12:
byte 13:
7 6 5 4
0 0 1 0 $ 0 0 _ _
bytes 14-18:
bytes 19-23:
bytes 24-25:
DAWNco • 3340 S. Lapeer Rd • Orion, MI 48359-1320 • Ph (248) 391-9200 • Fax (248) 391-9207 • sales@DAWNco.com
STX
where A is the CONTROL-1500 address
A
31h the status poll query command code
ETX
checksum
ACK
A where A is the CONTROL-1500 address
31h the status poll query command code
sat_name This field will contain the satellite name in upper case letters. If the
name does not occupy the entire field the name will be left justified and
the string will be padded with blanks. If a satellite name is not currently
displayed, this field will contain blanks.
sat_name status - binary data
3 2 1 0
0 0
0 1
1 0
position This field will contain the current antenna position, formatted in a manner
identical to how the position is displayed on the front of the unit, '0' to
'65535'. If a limit is active, the field will contain either 'CCW' or 'CW'.
Not Used
pol position If a Polarotor is present in the system this field will contain the current
polarization position, formatted in a manner similar to how the position is
displayed on the front of the unit, '0' to '98', or 'CC' or 'CW' if a limit is
active. As the Polarotor moves counter clockwise (as viewed looking
into the feed horn), the displayed numbers get greater.
If a rotating feed is present in the system, this field will contain a value in
the range of 0 to 92, 'CW' or 'CC'. The value in this field will be related to
the value displayed on the user interface of the controller by the following
formula ...
byte_24_25_position =user_interface_position / 11.
where
byte_24_25_position ... is the value returned in bytes 24 and 25.
Appendix E
displayed in upper case letters
displayed in lower case letters
sat_name not displayed
Communications Protocol 73