69
Instruction Manual
line-CVM-D32
7.- RS-485 COMMUNICATIONS
The
line-CVM-D32
devices have RS-485 communications with
MODBUS RTU ®
communications
protocol.
7�1�- CONNECTIONS
The RS-485 cable must be a twisted pair cable with shielding mesh (minimum 3 wires), and maximum
distance between the
line-CVM-D32
device and the master unit must not exceed 12m. in length.
A maximum of 32
line-CVM-D32
devices can be connected to the bus.
For communication with the master unit, a smart
RS-232
to
RS-485
network protocol converter must
be used.
B(-)
A(+)
S
RS-232 / USB / Ethernet / Profibus ...
PC
RS-485
RS-485
RS-232
USB
Ethernet
Profibus
...
A(+)
B(-)
S
A(+)
B(-)
S
24
23
22
A
23
22
Figure 31: RS-485 connection diagram�
Note:
Default values of the RS-485 communication:
19200 bps
,
No parity
,
8 data bits
and
1 stop bit
.