Siemens MJ-5 - Switches and Connections; Control Switches and Modes; Binding Posts and Terminal Strips

MJ-5 Communications Module
9
RTN
Signal Return
RXD
RXD
TXD
TXD
RTS
RTS
CTS
CTS
“RXD” is an input for Data Terminal Equipment (DTE) and an output for Data Communications Equipment (DCE).
“TXD” is an output for the DTE and an input for the DCE. Personal computer serial ports are configured as DTE
and the modems are configured as DCE. The communications module RS-232 connections implement DTE.
5.3.1 RS-232 Multi-drop Wiring
Multi-drop configurations require that the respective pins of the DTE devices be connected in parallel, Figure 7-6.
The standard pin assignments for RS-232 connectors are shown in Figure 7-7.
Note: For Figure 7-6, the RTU port is wired as “DTE”. When networking devices together, make sure the RTU
“data out” connects to the communications module Rxd, and the RTU “data in” connects to the communications
module Txd.
Figure 5-6 : RS-232 Multi-drop Configuration
Figure 5-7: RS-232 Connector Pinout
5.4 RS-232/485 Connections
The screw terminal block connector is keyed for proper insertion. Figure 7-8 shows the proper connector orientation.
Align the keys and insert the connector to interface to the RS-232/485 interface.
Figure 5-8: Screw Terminal Connection
1
1
6
9
5
13
14 25
Pin
Pin
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
20
9
22
*
*
*
Signal
Signal
Ground (Frame)
DCD
Txd
Txd
Rxd
Rxd
RTS
DTR
CTS
DSR
DSR
Ground (Signal)
Ground (Signal)
DCD
RTS
DTR
CTS
RI
RI
Shell (Frame Ground)
For Shielded Cable Connectors
Shell (Frame Ground)
DE9
DB25
G
N
D
RTN Da
ta
Rxd
Txd
CT
S
RT
S