Operating Instructions
Siemens Building Technologies / HVAC products B3099 20.10.2009 1 / 2
Operating Instructions SEZ50MB
Product Overview:
The SEZ50MB unit is a RS485 type Modbus communication interface (RTU mode only). It connects with
RWD controllers via RS232 interface for remote monitoring functions. SEZ50MB Modbus communication
can be developed by users according to Modbus Application Protocol Specification V1.1b
(www.Modbus.org), or users can use Siemens Modbus SW tool as the SEZ50MB Modbus interface.
Modbus Connection
The SEZ50MB Modbus Interface Unit enables remote monitoring on RWD devices on the same network
(Modbus). The BUS topology is recommended, i.e. one single bus.
A
M
odbus
RS485 Type
Max Cable Length = 1000 m
…
+
-
Ref GND
Ref
- +
SEZ50MB
RS232
RWDxx
RS232
Ref
- +
SEZ50MB
RS232
RWDxx
RS232
Ref
- +
SEZ50MB
RS232
RWDxx
RS232
+
-
Termination
Resistance of
both ends
150
Ω
RX
TX
GND
TX
RX
GND
D+
D-
RS232
-
TO
-
RS485
Converter
Isolated Converter Recommended
B
USB
USB
…
+
-
Ref
Ref
-
+
SEZ50MB
RS232
RWDxx
RS232
Ref
-
+
SEZ50MB
RS232
RWDxx
RS232
Ref
-
+
SEZ50MB
RS232
RWDxx
RS232
+
-
Termination
Resistance
of both ends
150 Ω
GND
D+
D
-
Modbus RS485 Type
Max Cable Length = 1000 m
RS232
-
TO
-
RS485
Converter
Isolated Converter Recommended
Power Supply Interface
G & G0 terminals are for AC 24 V SELV power supply (LED indicates power on).
Modbus RS485 Interface
+, - Differential Signals
Ref Differential COMMON
RS232 Interface to RWD Device (DB9 Connector)
A 1.5 meters long RS232 cable is provided together with SEZ50MB and the RS232 cable is one-to-one type
(the same pin numbers are connected at both ends of this cable). The DB9 male socket of the RS232 cable
will be connected to RWD device while the female plug will be connected to SEZ50MB.
Pin No. Descriptions Functions
1 Not Used Not Used
2 RXD Receive Input
3 TXD Transmit Output
4 Voltage Output 1 DC +12 V
5 Reference Ground RS232 0 V
6 Not Used Not Used
7 Voltage Output 2 DC -12 V
8 Not Used Not Used
9 Not Used Not Used
ON
1
2
3
4
5
6
7
8
Device Address Bit
The SEZ50MB device address can be set via an 8-way DIP switch and the valid addresses are 1 to 247.
DIP switch Position à
1 2 3 4 5 6 7 8
Address No. Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Broadcast Address (= 0)
0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1
User Addresses (= 1 to 247)
1 1 1 1 0 1 1 1
1 1 1 1 1 0 0 0
Reserved Address (= 248 to 255)
1 1 1 1 1 1 1 1
ON
1
2
3
4
Device Setting
The communication settings such as baud rate, parity and stop bits can be set via a 4-way DIP switch.
DIP switch Position Function Settings ON (1) or OFF (0)
ON 19200bps (Default)
1
Baud Rate Selection
OFF 9600bps
2, 3
Parity & Stop Bits
OFF
ON
OFF
ON
OFF
OFF
ON
ON
ODD Parity, 1 Stop Bit
Even Parity, 1 Stop Bit (Default)
None Parity, 2 Stop Bits
None Parity, 2 Stop Bits
ON No Function
4
Reserved
OFF No Function (Default)