Chapter 3: Installation and Setup
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 for the signal lines.
3.2.3 RS-485
RS-485 connections support 2-wire or 4-wire operation. In RS-485 mode, the transmitter is only enabled when the Hardened Serial Server is transmitting data on the line. This allows other devices to share the bus.
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 for the signal lines.
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 for the signal lines.
NOTE: Refer to Appendix B for connector pinout information.
Network
Serial connection | Serial device |
|
Figure 3-2. LES424A connections.
3.3 Connecting RS-232/422/485 Hardened Serial Servers to a Network
Ethernet Connection (10BASE-T/100BASE-TX)
When connecting a Hardened Serial Server equipped with a 10BASE-T/100BASE-TX network connection (RJ-45 connector) to an Ethernet network, use a standard unshielded twisted-pair cable. When installing this equipment in industrial or other electrically noisy environments, we strongly recommend that you use STP (shielded twisted pair) cable. The Hardened Serial Server has an automatic MDI-X interface that will sense the pinout of the network interface and provide a crossover connection if required.
3.4 Ethernet Passthrough Port
4-Port Hardened Serial Servers (LES424A) are equipped with an additional RJ-45 network port, also known as a passthrough port. This port can be used to connect additional Ethernet devices, such as a local workstation or second serial server, to the network.
Local Ethernet
device
Network
Figure 3-3. Ethernet passthrough port (on LES424A only).
