Grass Valley RSAT1 - Manual (Page 29)

Satellite Panel RSAT1 6. Annex
24 Operating Instructions - Rev. 3 / 7.2002
6.2 SERIAL PROTOCOL FOR THE DD35 SATELLITE PANEL
6.2.1 PREFACE
This protocol describes a point-to-point serial protocol.
The intention is to provide a robust flexible means to hook up specialized hardware
with a standard PC. Inside the specialized hardware is an industry single chip mi-
croprocessor.
6.2.2 ELECTRICAL SPECIFICATIONS
This protocol uses a full-duplex RS-232 conformant serial line without hardware
handshake.
6.2.3 COMMUNICATION PARAMETERS
Communication is asynchronous with 9600 Baud, 1 Start, 8 Data,
No parity, 1 Stop bit.
6.2.4 PROTOCOL DESCRIPTION
The datagram derived from the KERMIT packet format consists of
Start length type Data chksum end/cr lf
0x01 toascii(length) ... char(chk) 0x0d 0x0a
Each protocol field – except the data field – is one ASCII byte. The Data field may
be longer.
Length is the count of all following bytes up to and including chksum.
Type is the message type described later. Type is a printable ASCII character.
Data depends on type and is described later together with the type. Data is printa-
ble ASCII character(s).
For calculation of chksum the following C program is given. A value of ‘~’ in this
field indicates that the checksum was not calculated.