M03Q40G6-03 30/07/08
pag
27
11.
INTERFACCIAMENTO UNITA’ VIA RS 485
Below the indications for the serial connection ; refer anyway to the CLIVET “RS 485 NETWORKS –
GUIDELINES” document and ask for the COMMUNICATION PROTOCOL about the COMPACT electronics
-
The total length of each single serial line,
don’t have to be over 1000 metres
-
The potential difference between the “ground”
of two RS485 switches must be less of 7 V
-
Couple of conductors twisted and shielded
-
Section of conductor 0.22mm
2
…0,35mm
2
-
Nominal capacity between conductors < 50
pF/m nominal impedance 120
Ω
-
Recommended cable BELDEN 3105 A
TYPE OF NETWORK
The serial lines must be connected in bus typology, i.e. nodes to more points are not admitted
OK
NO !
SHIELD
-
It must be connected to a ground without
disturbances
-
Connected to round in only one point
-
Provide to the shield continuity during all the
serial cable extension.
Sistema di supervisione
12 V AC
C
N
1
C
N
1
19
18
20
21
20
18
19
21
RS-485
RS-232
gnd
-
+
Supervisor
TTL /
RS485
+
-
TO OTHER
UNITS
12 V AC
gnd
TTL /
RS485
-
gnd
+
