RS-485 Remote Control Protocol
Reference Guide: SM6610, SM6615, SM6620 and SM6625 Satellite Modulators
Page 6-5
ST.RE.E10152.2
Byte Ordering
Where a field consists of more than one byte, it must be ordered with the
most significant byte first.
Message Extensions
To allow for future enhancements, the receiver of messages from the
Modulator must not assume the location of the checksum based on the
message type. Doing this will allow for the message to grow in size and
still be received. If additional data is added to a message it will be added
at the end of the value field, thus allowing software written for an earlier
version of the message to still function.
Numeric Fields
A numeric field consists of 1 or more bytes. The bytes represent an ASCII
encoded hexadecimal value. The following ASCII characters are allowed in
a numeric field:
•
Numeric characters ‘0’ – ‘9’
•
Upper case letters ‘A’ – ‘F’
TEXT Fields
TEXT fields consist of 1 or more contiguous bytes. The field will normally
be a fixed number of bytes. Unused bytes should be set to ‘NUL’ (ASCII 0).
The following ASCII characters are allowed in a TEXT field:
•
Numeric characters ‘0’ – ‘9’
•
Upper case letters ‘A’ – ‘Z’
•
Lower case letters ‘a’ – ‘z’
•
Space character (ASCII 32
10
)
