Eurotech ZyWAN, User Manual

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ZyWAN - User Manual
18 110150-1001F
Serial Ports
The following tables show pin assignments for the serial ports.
COM1, COM2, COM3 (RS-232)
PIN SIGNAL NAME
1 Data Carrier Detect (DCD)
2 Receive Data (RX)
3 Transmit Data (TX) *
4
Data Terminal Ready (DTR) *
5
Ground
6 Data Set Ready (DSR)
7 Request To Send (RTS) *
8 Clear To Send (CTS)
9 Ring Indicator (RI)
* = output signals
COM3 (4-wire RS-485/422)
PIN SIGNAL NAME
1 NC
2 NC
3 RS-485/422 TX-
4
RS-485/422 RX-
5
GND
6
NC
7 RS-485/422 TX+
8 RS-485/422 RX+
9 GND
RS-485 / RS-422 wiring diagrams
When connecting RS-485 or RS-422 devices in a multidrop configuration, there must usually be a 120 Ω
termination resistor at one or both end devices in the network but NOT on any devices in the middle of the
loop. The ZyWAN provides a 4-wire RS-485/422 interface.
In RS-485 or RS-422 systems, the ground connection is optional. Typically, it is used to connect the cable
shield for a shielded, twisted pair cable. In the ZyWAN, the RS-485/422 ground is common with the RS-232
grounds, but it is isolated from the metal case. In order to avoid ground loops, connect the cable shield to the
RS-485/422 GND AT ONLY ONE POINT in the network.