Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
5-30
940331 is the default password. The password can be changed to any number from 0 to 999999
by the variable RS232_PASS. To change the password enter the command
V RS232_PASS=940331
which sets the password to the factory default.
Protocol of Port Communication
The RS-232 interface has two protocols of communication, because if the port is attached to a
computer it needs to have different characteristics than if used interactively. Consequently, there
are two primary styles of operation: terminal mode and computer mode.
When an operator is communicating with the analyzer via a terminal, the analyzer should be
placed into TERMINAL MODE, which echoes keystrokes, allows editing of the command line
using the backspace and escape keys, and allows recall of the previous command. When a host
computer or data logger is connected to the analyzer, it should be placed into COMPUTER
MODE, which does not echo characters received or allow the special editing keys. See
Table 5-10 for relevant commands.
Table 5-10: RS-232 Switching From Terminal Mode to Computer Mode
Key Function
Control-T (ASCII 20 decimal) Switch to terminal mode (echo, edit)
Control-C (ASCII 3 decimal) Switch to computer mode (no echo, no edit)
If the command line doesn't seem to respond to keystrokes or commands, one of the first things
you should do is send a Control-T to switch the command line interface into terminal mode.
Also, some communication programs remove CTRL-T and CTRL-C characters from the byte
stream, therefore these characters will not be sent to the analyzer. Check your communications
program owners manual.
Entering Commands in Terminal Mode
In terminal mode, all commands must be terminated by a carriage return; commands are not
processed until a carriage return is entered. While entering a command you may use the
following editing keys: