VEGA Phoenix PSI Data Fax Modem - Manual (Page 42)

PSI-DATA/FAX-MODEM/RS232
3-10 692302
3.3.2 RS-232 Interface
The modem and the PC or another device are connected via the RS-232 cable
PSM-KA-9SUB 9/BB/2 METER (Order No. 27 99 47 4). The cable is an interface
cable with 1:1 connected contacts.
• Use this interface cable to connect the modem to a free COM interface on the
PC.
In rare cases, when connecting a PLC or control system, DCE (Data
Communication Equipment) may be used instead of DTE (Data Terminal
Equipment), which is typical for a PC. If so, the following cables must be crossed
(null modem cable):
– TxD and RxD
– RTS and CTS
– DSR and DTR
If you do not know which type of interface is connected, you can determine the
connect configuration by testing (crossing cables).
Minimum configuration The minimum configuration only requires one connection for TxD, RxD, and GND
(software handshake).
This does not apply to the 3964R protocol for Phoenix Contact controller boards.
Only TxD, RxD, and GND are connected here, but no handshake protocol is
selected.
The modem must only be connected to devices which meet the requirements of
EN 60950 ("Safety of Information Technology Devices").