51
Instruction Manual
CVM-C4
7.- RS-485 COMMUNICATIONS
The
CVM-C4
devices have an
RS-485
communications port, with communications protocol:
MODBUS RTU ®
.
7�1�- CONNECTIONS
The RS-485 cable must be wired using twisted pair cable with mesh shield, leaving a maximum
distance between the
CVM-C4
and the master device of
1200 metres
.
A maximum of 32
CVM-C4
devices can be connected to this bus.
To establish the communications with the master device, we must use a smart RS-232 to RS-485
network protocol converter.
B
A
RS-485
S1 S2 S1 S2 S1 S2
I1
I2
I3
U1
U2 U3 UN
B
A
RS-485
S1 S2 S1 S2 S1 S2
I1
I2
I3
U1
U2 U3 UN
58
49 50
2
1
4
5
6
7
8
9
11
12 13
14
47 48
59 70 71 72
15 16 17 18
58
49 50
2
1
4
5
6
7
8
9
11
12 13
14
47 48
59 70 71 72
15 16 17 18
B(-)
A(+)
RS-232 / USB / Ethernet / Profibus ...
PC
RS-485
RS-485
RS-232
USB
Ethernet
Profibus
...
Figure 21: RS-485 connection diagram�
Note:
Default values of the RS-485 communication:
19200 bps
,
No parity
,
8 data bits
and
1 stop bit.
