4. REMOTE OPERATION
Page 69
© 2008 DH Instruments, a Fluke Company
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4.1
OVERVIEW
Most of the RPM4-E-DWT front panel functions can also be executed by commands from a remote
computer. The host computer can communicate with the RPM4-E-DWT using the RPM4-E-DWT’s COM1
RS232 port.
Before writing code using RPM4-E-DWT remote commands, familiarize yourself with its operating
principles by reviewing Section 3 of this manual.
4.2
INTERFACING
Sending a program message to the RPM4-E-DWT places it into
remote
mode. The remote indicator to
the right of the display window lights when the RPM4-E-DWT is in
remote
mode. It also flickers when a
program message is received. The menus usually accessed from the front panel are locked out while in
remote. The
[ESC]
key returns the RPM4-E-DWT to local operation unless the
<REMOTE>
program
message, which locks out all keypad operation, was sent to the unit.
4.2.1
RS232 INTERFACE
4.2.1.1
COM1
The RPM4-E-DWT COM1 RS232 interface is located on the back of the unit. It is a
9-pin male DB-9F connector configured as a DCE device. Data is transmitted out of
the unit using pin 2, and is received on pin 3. This allows a normal pin-to-pin DB-9M
to DB-9F RS232 cable to be used to connect to a DTE host.
Handshaking is not required or supported. The COM1 receive buffer is
80 bytes deep. If you overflow the buffer by sending too much data, the data will
be lost. Because of this, you
must
send a single program message at a time
and you
must
wait for the RPM4-E-DWT to reply from the previous command
before issuing another command.
Table 11.
COM1 pin designations and connections
RPM4-E-DWT COM1 DB-9F PIN DESIGNATIONS
PIN #
FUNCTION
DESCRIPTION
2
TxD
This pin transmits serial data from the RPM4-E-DWT to the
host.
3
RxD
This pin accepts serial data from the host computer.
5
Grn
This pin is the common return for the TxD and RxD signals.
IBM PC/XT DB-9F
CONNECTIONS
IBM PC/XT DB-9M TO RPM4-E-DWT
DB9F CONNECTION
DB-25M
DB-9F
DB-9M
DB-9F
2
3
3
3
3 2 2 2
7
5
5
5
