Campbell CR10 PROM, Руководство оператора

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SECTION 6. 9-PIN SERIAL INPUT/OUTPUT
6-10
To overcome the limitations of half duplex,
some communications links expect a terminal
sending data to also write the data to the
screen. This saves the remote device having to
echo that data back. If, when communicating
with a Campbell Scientific device, characters
are displayed twice (in pairs), it is likely that the
terminal is set to half duplex rather than the
correct setting of full duplex.
IF NOTHING HAPPENS
If the CR10 is connected to the SC32A RS232
interface and a modem/terminal, and an "*" is
not received after sending carriage returns:
1. Verify that the CR10 has power AT THE
12V AND GROUND INPUTS, and that the
cables connecting the devices are securely
connected.
2. Verify that the port of the modem/terminal is
an asynchronous serial communications
port configured as DTE (see Table 6.7-2).
The most common problems occur when
the user tries to use a parallel port, or
doesn't know the port assignments, i.e.
COM1 or COM2. IBM, and most
compatibles come with a Diagnostic disk
which can be used to identify ports, and
their assignments. If the serial port is
standard equipment, then the operators
manual should give you this information.
Some serial ports, e.g., the Super Serial Card
for Apple computers, can be configured as DTE
or DCE with a jumper block. Pin functions must
match with Table 6.7-2.
If you are using a computer to communicate
with the datalogger, communication software
must be used to enable the serial port and to
make the computer function as a terminal.
Campbell Scientific's TERM program (part of
the PC208 Datalogger Support Software)
provides this function for IBM PC/XT/AT/PS-2's
and compatibles. The port should be enabled
for 300, 1200, or 9600 baud, 8 data bits, 1 stop
bit, and no parity.
If you are not sure that your computer/terminal
is sending or receiving characters, there is a
simple way to verify it. Make sure that the
duplex is set to full. Next, take a paper clip and
connect one end to pin 2, and the other end to
pin 3 of the serial port. Each character typed
on the keyboard will be displayed only if
transmitted from the terminal on pin 2, and
received on pin 3 (if duplex is set to half, the
character will be displayed once if it is not
transmitted, or twice if it is transmitted).
IF GARBAGE APPEARS
If garbage characters appear on the display,
check that the baud rate is supported by the
CR10. If the baud rate is correct, verify that the
computer/terminal is set for 8 data bits, and no
parity. Garbage will appear if 7 data bits and
no parity are used. If the computer/terminal is
set to 8 data bits and even or odd parity,
communication cannot be established.