Xylem XL Series H-522 - Plus - Manual (Page 21)

XL™ Series
Hardware Options and Installation 2-7
Figure 2-5 RS-232 Connector
2.2.7 RS-232 Ports
The three RS-232 ports are used to connect to a PC, GOES Transmitter, modem, remote display,
or other serial equipment for standard serial communications. These ports are configured as a
DTE type of device. This means they will plug directly into a modem (a DCE type device), but
will require a NULL modem adaptor if connected to a PC (a DTE type device). The NULL
modem cable crosses the communication lines allowing two similar devices to communicate.
Figure 2-5 shows the pin out for all three ports. See the chapter covering the serial ports for
complete information on the port operations.
SERIAL PORT PIN-OUT
PIN DIRECTION NAME
1 Input Data Carrier Detect (DCD)
2 Input Receive Data (RD)
3 Output Transmit Data (TD)
4 Output Data Terminal Ready (DTR)
5 Ground (GND)
6 Input Data Set Ready (DSR)
7 Output Request To Send (RTS)
8 Input Clear To Send (CTS)
9 Input Ring Indicator (RI)