Agilent Technologies RS-232, Instruction Manual

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RS-232 and RS-485 Options for the senTorr Gauge Controller
1-6
DRA
FT
Operation
The user application must conform to the software protocol as specified (refer to
“Command Syntax and Definitions” on page 7). The senTorr's baud rate and address are
programmed through the front panel keypad. For successful operation, all units on the
network must be at the same baud rate and, to avoid contention, have different addresses.
All units are shipped from the factory with a default address of 00.
Upon receipt of a command, senTorr holds its RTS line to logic 1 (unasserted) while it
processes the command and returns any required data. If the host does not monitor its CTS
line (as in RS–485), it must limit the frequency of commands as follows.
❑
The host must allow 500 mseconds after sending an emission or degas on/off
command. Any bytes sent during that time overwrite each other.
❑
If a response is expected, the host waits to receive the response before starting the
next command.
While senTorr tolerates high speed communications, the application does not tie up senTorr
with incessant strings of commands so it can process pressure data from the gauge channels.
Setting Baud Rate and Address
The BAUD RATE key is used to display and set the serial communications baud rate, parity,
and the controller address (for use in a multi-drop communication link).
To set the baud rate and address:
1. Press BAUD RATE .
The IG display mantissa flashes the present baud rate.
2. Use the up/down arrows to select the desired baud rate:
1.2 (1200), 2.4 (2400), 4.8 (4800), 9.6 (9600), or 19.2 (19,200).
3. Press ENTER to save the baud rate setting and to advance to the parity setting display in
the IG exponent.
4. Use the arrow keys to select no (n) , even (E) , or odd (0) parity.
5. Press ENTER to save the parity setting.
The controller address setting flashes in the IG mantissa.