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3. Description of functions
The PW100 is a transparent Level Converter from several interfaces to M-Bus for up to 100 meters. The
device allows external connected controllers such as a building control, a DDC or a PC to read the connected
meters by use of an M-Bus software (not in scope of delivery). The PW100 can also be used as a Repeater
for extension of M-Bus networks relating to the cable length and number of meters.
3.1 Interface multiplexer / switch
An internal microcontroller handles the bus control to just give one interface access to the M-Bus even with
multiple connected interfaces. This ensures that systems do not interfere with each other during the commu-
nication, when two or more systems are connected, for example a BMS via RS485 and a PC via USB. This
automatic switch operates on the principle "first come, first served", i.e. when an interface sends a signal to
the M-Bus, this interface takes control of the M-Bus and has exclusive access to communication. The "ACTIVE"
labeled LED indicates the activity status of the internal interface switch. While the LED is lit, one of the six
possible interfaces is active. The other interfaces are disabled at this time and cannot access the M-Bus. The
active interface remains enabled about 3 seconds after the last communication. Another interface can occupy
the M-Bus as soon as the LED goes off.
3.2 RS232C interfaces
The PW100 has two independent RS232C interfaces, both of them as a 9-pin D-SUB as 3-pin screw terminals.
The RS232C pin assignments are:
RX = PC transmits to M-Bus, TX = PC receives from M-Bus, GND = Signal ground
If you want to connect a D-SUB cable, please use the additional, optional cable KA006 with 3 open wires.
To link to a PC (1: 1 connection), connect the 3 wires as follows:
PW100 · User Manual Version 1.0 - 11/2020
D-SUB
Signal
Pin 1
DCD (data carrier detect)
Pin 2
RXD (PC receives data)
Pin 3
TXD (PC transmits data)
Pin 4
DTR (data terminal ready)
Pin 5
GND (signal ground)
Pin 6
DSR (date set ready)
Pin 7
RTS (request to send)
Pin 8
CTS (clear to send)
Pin 9
RI (ring indicator)
Funktion PW100
unused
M-Bus sends data to PC
PC receives data from M-Bus
unused
GND
unused
unused
unused
unused
PW100
Farbe (Klemme)
Green (TX)
Yellow (RX)
Black (GND)
6
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