User guide

38
Remote Interface Reference
RS-232/422 Configuration
4.3 RS-232/422 Configuration
The Model 187 allows several parameters related to the RS-232/422
interface to be configured by the user. See the
Comm Menu
description in
paragraph 3.3.10 on page 22 for illustrations of the menus provided for
configuring the Model 187 serial interface.
The
Comm Menu
provides menus to configure the following (the defaults
are shown in bold):
Baud Rate
: 1200, 2400, 4800,
9600
Parity and Data Bits
: Even Parity/7 Data Bits, Odd Parity/7 Data
Bits,
No Parity/8 Data Bits
Number of Start Bits
:
1 bit
(fixed)
Number of Stop Bits
:
1 bit
or 2 bits
Flow Control
:
None
or SW (XON/XOFF)
4.3.1 Serial Port Connector
An
IBM-compatible computer’s serial port can be directly connected to the
Model 187 via a standard DB9 female-to-DB9 male PC modem cable if the
Model 187 is configured for RS-232. Refer to your computer’s
documentation to determine which serial ports are available on your
computer and the required connector type. The cable to connect two DB9
connectors is wired directly, i.e. pin 1 to pin 1, pin 2 to pin 2, etc. If a DB25
connector is required at the computer interface, the connector translation
is provided in the
Appendix
.
The Model 187, when configured for RS-232, uses only three wires of the
rear-panel DB9 connector: pin 2 (transmit), pin 3 (receive), and pin 7
(common). The RS-232 (and RS-422) pinout is fully documented on page 60
in the
Appendix
. The Model 1887 is classified as a DCE (Data
Communication Equipment) device since it transmits data on pin 3 and
receives data on pin 2. The computer or terminal to which the Model 187 is
attached must do the opposite, i.e., transmit on pin 2 and receive on pin 3
(the requirements for a DTE, or Data Terminal Equipment device). If a
serial-to-parallel converter is used, it must be capable of receiving data on
pin 3 or the cable connected to the Model 187 must interchange the wires
between pins 2 and 3.
Optional RS-422 connector pinout is provided in Table A-4 on page 61.
4.3.2 Termination Characters
All
commands and queries are transmitted and received as ASCII values
and are case insensitive. The Model 187 always transmits
<CR><LF>
(i.e.
a
carriage return
followed by a
linefeed
) at the end of an RS-232