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Teledyne API Model 465L O
3
Monitor Operation Manual
58 05509F DCN6409
8.4. RS-485 Configuration
RS-485 is commonly used for factory automation busses with a computer or PLC acting as a
master. The communications protocol used for the RS-485 configuration is MODBUS RTU.
For details on the MODBUS RTU specification, please see http://www.modbus.org/.
With the instrument configured for RS-485, connection can be made to the DB-9 connector,
labeled “RS232/485”, or to the three “COM” pins on the “General I/O” connector. Table 8-3
below details the pinouts of these two connectors:
Table 8-3: RS-485 Connector Details
Function DB-9
Connector Pin
(SW2 – DCE)
General I/O
Connector
RS485 - A 2 ‘T’
RS485 - B 3 ‘R’
Ground 5 ‘G’
Note that for RS-485, the DTE-DCE switch should always be set to DCE. See Section 8.2 for
details on changing this configuration.
The serial port setup for RS-485 configuration is shown in Table 8-4 below:
Table 8-4: RS-485 Port Setup
Property Value
Baud Rate 57600
Data Bits 8
Parity None
Stop Bits 1
Flow Control None