Grass Valley Performer-HD - Manual (Page 42)

3-10 Performer-HD Instruction Manual
Section 3 — Operation and Maintenance
Performer-HD ASCII Protocol
Performer-HD ASCII allows control of the Performer-HD from a host ter-
minal or computer using standard ASCII characters. Multiple Performers,
each assigned a unique address, may be controlled over a common RS422
bus. All characters are 7-bit ASCII (the eighth data bit out of the Performer-
HD port is ignored). A ninth data bit may be used for parity if desired.
Command Line
A command line consists of series of bytes in the following format:
All bytes are hex ASCII (characters 0-9 [30H-39H] and A-F [41H-46H]), ex-
cept for
. A hex ASCII character specifies 4 bits or 1 nibble of informa-
tion and is used in high/low pairs to specify a complete byte of
information. Received ASCII nulls (00H), spaces (20H), and line feeds
(0AH) are ignored and are not included in the byte count.
Command bytes have the following values:
If the value is different from the value set at Per-
former-HD switch S1, the command and all subsequent characters are ig-
nored by the Performer-HD until a new message is initiated using a
carriage return. The carriage return purges previously received data, and
must start each command line.
If a carriage return is received before a command string is complete, the
Performer-HD will display
ERR P for about half a second in the status dis-
play. ERR P will also be displayed on receipt of parity/overrun, checksum,
or syntax errors.
Table 3-2. Command Bytes Values
Command Description
REQUIRED carriage return character (0DH)
0-F, high nibble of Performer-HD switch 1 address
0-F, low nibble of Performer-HD switch 1 address
0-F, high nibble of byte count for
0-F, low nibble of byte count. Count must not exceed 251 (FBH).
0-9, A-Z. Zero or more command strings (see Command Strings).
Number of characters is