DH Instruments PPC3 - 4 Remote Operation; Overview; Interfacing; Rs232 Interface

4. REMOTE OPERATION
Page 81 © 2002-2007 DH Instruments, a Fluke Company
4
4
.
.
R
R
E
E
M
M
O
O
T
T
E
E
O
O
P
P
E
E
R
R
A
A
T
T
I
I
O
O
N
N
4.1 OVERVIEW
Most of the PPC3 front panel functions can also be executed by commands from a remote computer.
The host computer can communicate to the PPC3 using the PPC3 COM1 RS232 port or the IEEE-488 port.
Before writing test code which makes use of PPC3 remote commands, familiarize yourself with its
operating principles by reading Section 3 of this manual.
4.2 INTERFACING
Sending a program message to the PPC3 places it into remote mode. The remote indicator to the right
of the display window lights when the PPC3 is in remote mode. It will also flicker 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 PPC3 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 PPC3 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 PPC3 to reply from the previous command before
issuing another command.
Table 14. COM1 Pin Designations and Connections
PPC3 COM1 DB-9F PIN DESIGNATIONS
PIN # FUNCTION DESCRIPTION
2 TxD This pin transmits serial data from the PPC3 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 PPC3 DB9F
CONNECTION
DB-25M DB-9F DB-9M DB-9F
2 3 3 3
3 2 2 2
7 5 5 5