Serial tally, Changing tally port serial settings – Grass Valley Switcher Products User Manual
Page 15
Switcher Products — Protocols Manual15
Serial Tally
Serial Tally
The switcher provides a serial tally interface that provides the necessary
information to trace any tally path within the switcher.
The serial protocol is based on RS-422 asynchronous serial communications
at 76.8 kb, 8 data bits, 1 stop bit, and no parity as a default. Other baud rates
(9600, 19,200, 38,400, 57,600, and 115,200) and odd or even parity selections
can be selected for contribution tally but the lower rates reduce throughput
and hence latency in reporting tally. 76.8 kb/field with no parity yields
about 128 characters per field and was assumed for all transmission times
unless otherwise noted. At 9600 baud and even or odd parity, the link only
supports 14 characters per field, making the link virtually useless for real
time tally (contribution tally would require 16 fields to transmit). See
for specific timing information.
The serial tally interface uses binary protocols with easily identifiable
message boundaries. All communication is from the switcher frame to the
external device. Multiple listeners can be connected to this port. External
devices should not transmit information on either pair of the link. The
switcher does not listen to this port, it only speaks.
The contribution tally information is currently output to port 5 on the
Kalypso system, and port 2 on the Zodiak system. The ability to configure
switcher serial ports for different purposes is currently under develop-
ment.
Changing Tally Port Serial Settings
At the time of publication, the switcher does not have a menu to change
serial port settings. The contribution tally baud rate can be changed by
editing the text file "mfPorts.cfg" located in the root of the frame's hard
disk. The file can be FTPed to a workstation, edited with any text editor and
FTPed back. The frame can then be reset to activate the new baud rate. If
the file is not recognized during frame boot up, a default will be created
replacing an existing one. The default uses 76.8 Kb.
The following sample indicates what the file should look like for 115.2 Kb
on a Kalypso system.
PORT5:115200,N,8,1 ; (Port:X:BaudRate,Parity,DataBits,StopBits)
PORT5: identifies which port will be affected by the remaining information
on the line. Currently only the tally contribution port (port 5 on Kalypso,
port 2 on Zodiak) can be set using this mechanism.
Respectively, the remaining comma separated information is:
Baud Rate: 9600, 19200, 38400, 57600, 76800 or 115200
Parity: N for none, O for odd or E