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2.4.4 RS232/RS485 Serial Communications Port
A bi-directional RS232/485 Serial Port Interface is provided that can be used for data
acquisition and instrument control. All that is required to use this interface is a computer
with a serial communications port (COM port) and terminal software. Three pins are
provided on the I/O connector for serial communications as shown in Table 2-3.
Table 2-3 Serial Port Pins
Label Description
SERIAL TX Serial Transmit (RS485 – A)
SERIAL RX Serial Receive (RS485 – B)
SERIAL GND Serial Ground (RS232 Only)
The Serial Port can be configured for either RS232 or RS485. The standard factory
configuration is RS232. For direct connection to a PC or Laptop, RS232 should be used.
For a permanent connection into a data acquisition system, RS485 is recommended
because it has better noise immunity and is more reliable when communicating over
longer distances. See Appendix A for details on changing the Serial Port configuration.
Figure 2-5 below shows typical connections using RS232 and RS485. Note that the
RS485 connection does not use the SERIAL GND pin.
Figure 2-5 Typical RS232 and RS485 Connections
See Chapter 5 for information on the Serial Communications protocol used by the
M460H.
SERIAL TX
SERIAL RX
DB9-FEMALE
RS232
SERIAL TX
SERIAL RX
RS485-A
RS485-B
RS485
SERIAL GND
P/N 03662D Teledyne API Model 460H O
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Monitor Operator Manual - Page 17