Laser beta lasermike LS8000-3 - Manual (Page 56)

LaserSpeed 8000-3 Instruction Handbook
Interfacing with the LS8000-3
Part No. 93463 / Drawing No. 0921-01561 Page 56 of 221 Revision A (Sep 2007)
DB9 Connector
The 9-pin interface port contains the RS-422 interface pins for high speed,
long distance communication with the LS8000-3, the Analog Output, and the
Measurement Synchronization Input pins. The connector is a standard 9-Pin
male D-Sub connector. It is shown below looking at the gauge's rear panel
with the gauge baseplate down.
Pin Description
1 RS-422 Transmit + (from LS8000-3 to host)
2 RS-422 Transmit – (from LS8000-3 to host)
3 RS-422 Receive + (from host to LS8000-3)
4 RS-422 Receive – (from host to LS8000-3)
5 Signal Ground for Inputs/Outputs/Serial
6 Analog Output Voltage
7 Analog Output Ground
8 Measurement Synchronization Input +
9 Measurement Synchronization Input -
RS-422 Transmit (+/-) and Receive (+/-) (Pins 1-4)
These pins comprise the RS-422 interface port. The RS-422 communications
port can be used at speeds up to 230kBaud over long distances. The
transmission cable should be a shielded, twisted pair cable. RS-422 uses
balanced pairs for both transmission and reception, so the +/- lines for the
Transmit and Receive pairs should be paired as shown. To minimize
reflections, the transmit lines from the gauge should be terminated with a
resistor matching the characteristic impedance of the cable (100Ω) as shown
below. The cable shield or drain wire should be attached to the chassis
ground at both ends of the cable. At the gauge end, a DB9 connector with a
metal backshell should be used, and the cable shield should be terminated to
the backshell. The cable jacket should be suitable for the environment to
which the cable will be exposed.