5 Installation
Page 5-2
gas-net
C1 and C2
5.2.2 MSER2 Serial Process Board
The MSER2 serial process board provides two interfaces supporting V24
(RS232) as well as RS422 and RS485. The table below shows the assignment
of the individual pins:
Signal Assignment
TXD
RS232: Transmitted data
RXD
RS232: Received data
RXB
RS422/RS485: Received data (B)
RXA
RS422/RS485: Received data (A)
TXB
RS422/RS485: Transmitted data (B)
TXA
RS422/RS485: Transmitted data (A)
SGD
Signal ground
SCH Shield
An MSER2 board must always be installed in the device if an ultrasonic gas flow
meter (type Q.Sonic or FLOWSIC) is connected via RS485. Another application
of an MSER2 board is the connection of a host computer via RK512/3964R or
MODBUS protocol or the connection of a GPS receiver for the time synchroni-
zation.
Notes:
•
When RS422 and RS485 are used, a terminating resistor of 120 ohms may
be required in the receiver between RXB and RXA, depending on the cable
length.
•
In case of RS485, you have to externally connect RXB to TXB and RXA to
TXA.
Please pay attention to the specification of the individual protocols. For instance,
there are protocols that render a connection via RS485 impossible (e.g. in case
of RK512).
5.2.3 Serial interface DSS
The serial interface DSS consists of a SUB-DB 9 female connector mounted on
the front and serves to connect the
gas-net
C1 or C2 to other devices, such as a
laptop or PC. A connecting line to the computer can be supplied as accessory
equipment. A standard COM connection (one-to-one connection) is not per-
missible.
