Network Design Considerations 2-5
SIMATIC TIWAY I Series 500 NIM User Manual
2.2 RS-232-C Cable Installation
The physical layer in TIWAY I provides a modem interface for synchronous
or asynchronous modems at data transmission rates up to 115.2K bits per
second. The modem interface provides standard signals, as defined in
Table 2-1, for control of two-way alternate data transmission using both half
and full duplex modems. The modem interface is a standard “Type E” DTE
configuration as defined in Section 5 of EIA RS-232-C. This interface uses a
male (plug) 25-pin D-type connector on the communication cable. The
circuits and pin assignments for the RS-232-C connector are shown in
Table 2-1.
Table 2-1 RS-232-C Connections
Pin ISO # RS–232-C Name – Function
1 101 AA –Protective Ground (chassis)
2 103 BA –Transmitted Data
3 104 BB –Received Data
4 105 CA –Request to Send (RTS)
5 106 CB –Clear to Send (CTS)
6 107 CC –Data Set Ready (DSR)
7 102 AB –Signal Ground
8 109 CF –Received Line Signal Detector/
Data Carrier Detect (RLSD/DCD)
15 114 DB –Transmitter Signal Element Timing
17 115 DD –Receiver Signal Element Timing
20 108/2 CD –Data Terminal Ready (DTR)