8.3.RS-232 Configuration
The RS-232 configuration is usually used when making a one-to-one connection between the instrument and a single computer or PLC. The communications protocol used for the RS-232 configuration is MODBUS RTU. For details on the MODBUS RTU specification, please see http://www.modbus.org/.
With the instrument configured for RS-232, connection can be made to the DB-9 connector, labeled “RS232/485”, or to the three “COM” pins on the “General I/O” connector. Only one of these connections should be used, the other must be left un- connected. Table 8-1below details the pinouts of these two connectors:
Table 8-1: RS-232 Connector Details
Function | DB-9 | DB-9 | General I/O |
| Connector Pin | Connector Pin | Connector |
| (SW2 – DTE) | (SW2 – DCE) | |
Transmit (Tx) | 3 | 2 | ‘T’ |
Receive (Rx) | 2 | 3 | ‘R’ |
Ground | 5 | 5 | ‘G’ |
NOTE
A DTE-DCE switch is provided so that the instrument can be connected to another device using either a straight-through or crossover (Null-Modem) cable. See Section 8.2 for details on changing this configuration.
The serial port setup for RS-232 configuration is shown in Table 8-2below:
Table 8-2: RS-232 Port Setup
Property | Value |
Baud Rate | 57600 |
Data Bits | 8 |
Parity | None |
Stop Bits | 1 |
Flow Control | None |
P/N 06160D DCN6409 Teledyne API Model 465M O3 Monitor Instruction Manual - Page 45