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If you are going to use any other setting, you must set up the appropriate settings
in the System Instrument using the following commands
COMM:SER[n]:REC:BAUD <rate> sets BAUD rate
COMM:SER[n]:REC:SBITS <bits> sets number of stop bits
DIAG:COMM STOR saves settings so they will be
kept through a reboot.
NOTE Because the special formatting for binary files uses all 8 bits, the number of data
bits must be set to 8 and parity checking must remain OFF for the driver files to
transfer properly.
Pacing the Data Since the RS-232 interface is asynchronous, it is possible for the computer that is
doing the download to overrun the System Instrument. This would cause part of
the driver to be lost. To prevent this from happening, you should enable
hardware handshake (either RTS or DTR) or software handshake
(XON/XOFF).
The default configuration for the E1405 Command Module is for software
handshake enabled and hardware handshake disabled. To make sure that
software handshake is enabled for the command module use the
SYST:COMM:SER:PACE? query. To set up software handshake you can use
the following commands:
SYST:COMM:SER:PACE:THR:STOP? MAX
to find the maximum number of characters to fill the input
buffer.
SYST:COMM:SER:PACE:THR:STOP < max-20>
to set the threshold for stopping data to the maximum size of
the input buffer minus 20 characters.
SYST:COMM:SER:PACE:THR:STAR 0
to set the start buffer level to zero. This makes sure that the
input buffer is completely flushed whenever transmissions are
stopped.
SYST:COMM:SER:PACE:XON
to enable the software handshake protocol.
The start threshold is not critical as long as it is less than the stop threshold. The
stop threshold must be set low enough to handle the maximum number of
characters that are likely to be received at the System Instrument after it sends
the XOFF signal.
Hardware handshake can be set up to use either the DTR (Data Terminal
Ready) line or the RTS (Ready to Send) line. These modes can be set with the
SYST:COMM:SER:CONT:DTR IBFULL command (to set for DTR) or
SYST:COMM:SER:CONT:RTS IBFULL command (to set for RTS). You may
wish to turn software handshake OFF using the
SYST:COMM:SER:PACE NONE command, though the system will operate
with both protocols enabled. When the input buffer of the System Instrument is
not full (number of characters in the input buffer is less than the high
threshold), the specified hardware line will be asserted. When either hardware
5-12 Downloading Device Drivers