3200 Series
Part No HA028651 Issue 7.0 Apr-09 13
2.15
Digital Communications
Optional.
Digital communications uses the Modbus protocol. The
interface may be ordered as EIA232 or EIA485 (2-wire).
In 3216 controllers only, EIA422 (4-wire) is available as
option 6XX.
☺
Digital communications is not available if Remote
Setpoint is fitted
☺
Cable screen should be grounded at one point only
to prevent earth loops.
•
Isolated 240Vac CAT II.
EIA232 Connections
EIA485 Connections
2.15.1.1
EIA422 Connections (3216 only)
☺
If EIA422 serial communications is fitted, the CT and
LA digital input option is not possible since EIA422 shares
the same terminals as the CT and LA.
☺
The KD485 communications converter is
recommended for:
•
Interfacing 4-wire to 2-wire connections.
•
To buffer an EIA422/485 network when more than
32 instruments on the same bus are required
•
To bridge 2-wire EIA485 to 4-wire EIA422.
Common
Rx A(+)
Tx B(-)
Screen
Local ground
Com
Rx
Tx
HD
HE
HF
220
Ω
termination
resistor
* EIA232/EIA485 2-wire
communications converter
eg Type KD485
Daisy Chain to
further
controllers
Com
220
Ω
termination
resistor on
last
controller in the line
Twisted pair
Tx Rx Com
Rx Tx Com
Screen
RxB/
TxB
RxA/
TxA
*
Common
Rx A(+)
Tx B(-)
HD
HE
HF
Com
Tx
Com Rx Tx
Screen
no connection
Rx+
Rx-
Common
Tx+
Tx-
Daisy Chain
to further
controllers
Twised
pairs
220
Ω
termination
resistor
220
Ω
termination
resistor on last
controller in the
line
EIA232 to EIA422/EIA485 4-
wire communications
converter
Eg Type KD485
RxB Com TxA
RxA TxB
Com Tx Rx
CT
C
LA
HD
HE
HF
Screen