Relay MR004C User Manual page 4

LED signals
:
RS232 interface:
The M-Bus can be accessed via an RS232C interface. The signals TXD, RXD and GND
(PC notations) are wired to terminals and to both DB9 connectors at the housing. The
upper DB9 socket (female) is designed for a PC and the lower DB9 plug (male) for a
modem. Only one of these three connectors can be used simultaneously. You can
attach a 1:1 serial cable to PC or the modem cable to modem. The modem must be
configured before it is connected (see addendum: "Modem configuration").
Pinning of DB9 connectors:
Pin Socket
2 RXD
3 TXD
4 -
5 GND
7 RTS
8 CTS
Pin 1, 6 and 9 are not connected
RS485 interface:
The PW60 normally activates the receive mode on the RS485. On reception of data
from the M-Bus slaves it switches to transmit mode (RS485 transmitter active). About
37ms after the last received data bit (0) the receive mode is re-entered. The RS485
interface of the PW60 is not addressable. There is an internal line termination of 1kΩ
inside the PW60. A stronger line termination of 120Ω can be obtained by connecting a
resistor of 130Ω between the terminals S+ and S-.
Simultaneous use of interfaces:
In case of a local readout using the keyboard of the remote display or during an
automatical readout the RS485 and RS232 interfaces do not have access to the M-Bus.
These functions and the contemporary use of the RS485 and RS232 interfaces can
produce temporary disturbances in communication.
Exchange of the fuse:
Over voltages on the power supply input may cause the fuse to blow. Please switch off
or disconnect the mains power (danger of life) before inserting a new fuse (type 5x20
250V 0,16A slow blow / 5x20 110V 0,25A slow blow for –US version). The fuse is
removed by pulling the fuse holder. You can use a screw driver to open the fuse holder.
4 07.03.02, Version 1.2
GmbH, Stettiner Str. 38, D-33106 Paderborn
Power (green):
Slave (yellow):
Max (yellow):
Short (red):
Plug Usage socket
TXD Transmit to PC
RXD Receive from PC
DTR Unused
GND Ground potential
CTS Handshake unused
RTS Always active
Power supply is O.K.
M-Bus slave is transmitting
Maximum current exceeded
Over current (short circuit)
Usage plug
Receive from modem
Transmit to modem
Always active
Ground potential
Always active
Handshake unused
User manual MR004DL/FA