29
4 RS-232 Communication/Data Logger Option
The RS-232 communication/data logger option provides a 25-pin D-type connector on
the rear panel of the instrument for serial communications and data logger function.
Serial port connector and cabling
An IBM-compatible computer’s serial port can be directly connected to the Model
186 via a standard PC modem cable. 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 DB25 connectors is wired directly, i.e. pin 1
to pin 1, pin 2 to pin 2, etc. If a DB9 connector is required at the computer interface,
the connector translation is provided in the Appendix.
The Model 186 uses only three wires of the rear-panel DB25 connector: pin 2
(transmit), pin 3 (receive), and pin 7 (common). There is no software or hardware
handshaking. The Model 186 is classified as a DCE (Data Communication
Equipment) device since it transmits data on pin 3 and receives data on pin 2. The
instrument to which the Model 186 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 186 must interchange the wires between
pins 2 and 3.
Command/return termination characters
All commands are transmitted and received as ASCII values and are case insensitive.
The Model 186 always transmits
<CR><LF>
(i.e. a
carriage return
followed by a
linefeed
) at the end of an RS-232 transmission. The Model 186 can accept
<CR>
,
<LF>
,
<CR><LF>
, or
<LF><CR>
as termination characters from an external
computer.
The simplest method for communicating with the Model 186 via RS-232 is by using
the interactive mode of a commercially available terminal emulation program. The
Model 186 transmits and receives information at various baud rates and uses 8 data
bits, no parity, and 1 stop bit. When the Model 186 receives a terminated ASCII
string, it always sends back a reply as soon as the string is processed.
When sending
commands to the Model 186, you must wait for the reply from the Model 186 before
sending another command even if the reply consists of only termination characters.
Otherwise, the shared input/output command buffer of the Model 186 may become
corrupted.
Summary of Contents for 186
Page 3: ...2 Introduction ...
Page 13: ...12 Installation Configuring power ...
Page 23: ...22 Calibration Approximate Calibration ...
Page 29: ...28 Operation Sensor contamination ...
Page 37: ...36 RS 232 Communication Data Logger Option Error Codes ...
Page 47: ...46 IEEE 488 Communication Option Serial Poll Status Byte ...
Page 55: ...54 Virtual Instrument Operation Running multiple GPIB devices ...
Page 65: ...64 Index ...