Chapter 3: Installation and Initial Setup
3. Installation and Initial Setup
NOTE: In this section, devices to be connected to the Modbus Hardened Serial Server’s serial connections are simply referred to as the “Modbus network.”
3.1 Connecting the Power Supply
Connect a DC power supply to the power terminals on the side of the Modbus Hardened Serial Server. Polarity of the wires is indicated on the label on the side of the Modbus Hardened Serial Server. Acceptable voltages are between 10 VDC and 58 VDC. The power supply must be capable of supplying 4 watts to the LES431A.
2-wire terminal block connector
Figure 3-1. LES431A power supply connections.
3.2 Connecting Modbus Hardened Serial Servers to Modbus Networks
The Modbus Hardened Serial Servers can be connected to Modbus networks using RS-232, RS-422, RS-485 2-wire, or RS-485 4-wire. The LES431A uses either (1) DB9 M connector or (1) 5-position terminal strip.
3.2.1 RS-232
RS-232 connections support eight signal lines plus Signal Ground. Signals are single-ended and referenced to Ground. Default communication parameters are 9600, 8, N, 1, and no flow control implemented.
3.2.2 RS-422
RS-422 connections support two signal pairs: TDA (-), TDB (+), RDA (-), RDB (+), and GND. The data lines are differential pairs (A and B) in which the B line is positive relative to the A line in the idle (mark) state. In RS-422, the transmitter is always enabled. Signal Ground provides a common mode reference.
3.2.3 RS-485
RS-485 connections support 2-wire or 4-wire operation.
When configured for 4-wire operation, the connection supports two signal pairs: TDA (-), TDB (+), RDA (-), RDB (+), and GND. This makes full-duplex operation possible. The data lines are differential pairs (A and B) in which the B line is positive relative to the A line in the idle (mark) state. Signal Ground provides a common mode reference.
When configured for 2-wire operation, the connection supports one signal pair: Data A (-) and Data B (+). These lines transmit and receive signals using half-duplex operation. The data lines are differential with the Data B line positive relative to Data A in the idle (mark) state. Signal Ground provides a common mode reference.
Connecting the Modbus Hardened Serial Server
The LES431A has one serial connection that supports RS-232, RS-422, and RS-485 (2- and 4-wire). The unit has two connectors: a DB9 male connector and a 5-position terminal block.
