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rial interface parameters menu are the BAUD rate, the sample rate, the duplex
mode, and the linefeed parameter.
8.1.2.1 Baud Rate
The baud rate is the first parameter in the menu. The display will prompt with
the baud rate parameter by showing “BAUd”. Press “SET” to choose to set the
baud rate. The current baud rate value will then be displayed. The baud rate of
the 9140 serial communications may be programmed to 300, 600, 1200, 2400,
4800, or 9600 baud. The baud rate is pre-programmed to 1200 baud. Use “UP”
or “DOWN” to change the baud rate value. Press “SET” to set the baud rate to
the new value or “EXIT” to abort the operation and skip to the next parameter
in the menu.
8.1.2.2 Sample Period
The sample period is the next parameter in the menu and prompted with
“SPEr”. The sample period is the time period in seconds between temperature
measurements transmitted from the serial interface. If the sample rate is set to 5
for instance then the instrument will transmit the current measurement over the
serial interface approximately every five seconds. The automatic sampling is
disabled with a sample period of 0. Press “SET” to choose to set the sample pe-
riod. Adjust the period with “UP” or “DOWN” and then use “SET” to set the
sample rate to the displayed value.
8.1.2.3 Duplex Mode
The next parameter is the duplex mode indicated with “dUPL”. The duplex
mode may be set to half duplex (“HALF”) or full duplex (“FULL”). With full
duplex any commands received by the thermometer via the serial interface are
immediately echoed or transmitted back to the device of origin. With half du
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plex the commands are executed but not echoed. The default setting is full du
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plex. The mode may be changed using “UP” or “DOWN” and pressing “SET”.
8.1.2.4 Linefeed
The final parameter in the serial interface menu is the linefeed mode. This pa
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rameter enables (“On”) or disables (“OFF”) transmission of a linefeed charac
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ter (LF, ASCII 10) after transmission of any carriage-return. The default setting
is with linefeed on. The mode may be changed using “UP” or “DOWN” and
pressing “SET”.
8.1.3 Serial Operation
Once the cable has been attached and the interface set up properly the control
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ler immediately begins transmitting temperature readings at the programmed
rate. The serial communications uses 8 data bits, one stop bit, and no parity.
The set-point and other commands may be sent via the serial interface to set the
temperature set-point and view or program the various parameters. The inter
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9140 Dry-well Calibrator
User’s Guide
34