FCI ST100A Series, Installation, Operation And Maintenance Manual

Page: 37 / 170

ST100A Series Flow Meter INSTALLATION
Fluid Components International LLC 29
Modbus Connections
Referencing
Figure 25 below connect the Modbus device/network to Phoenix connector J8 on the main board (not to be confused with the
auxiliary board J8 connector that provides the 3
rd
4-20 mA output). Note that the J8 connector is also used for F
OUNDATION
Fieldbus and
PROFIBUS wiring (only one interface can be active at a time). Connector J8 accepts 24–12 AWG (0.2 mm
2
– 1.5 mm
2
) wire (refer to Table
2 , page 21 for wire size vs. length info). It is recommended that wiring have a flammability rating of UL 2556 VW-1 or equivalent.
Figure 25 – Modbus/PROFIBUS/Fieldbus Connections, J8
C01531-1-1
1
2
3
J12 J13
J10
T1
1.
2.
3.
B (+),
FIELDBUS_ A
RETURN
A (–),
FIELDBUS_B
J25
J21
TB1
1 2 3
J11
J9
MAIN BOARD
Modbus/PROFIBUS/Fieldbus
Connector J8
Jumpers J12 & J13 set for
Modbus configuration
(positions 1 & 2)
Line Configuration Jumpers
J9, J10 & J11 (see Table in manual)
POWER SUPP LY BOARD
(Under Main Board)
Connect the ST100A Series to a Modbus device/network using a 2-wire RS-485 connection scheme as shown in Figure 26 below. For
details on Modbus operation refer to Modbus Operation , page 77 .
Figure 26 – Modbus Wiring
RS-485 MASTER
2-WIRE ONLY DEVICE
DEVICE 1 DEVICE 2 DEVICE 3
One twisted wire pair
plus Gnd/Common.
To remaining
RS-485 Devices
DATA (B)+
DATA (A)-
GND
D
AT
A
(B
)+
D
AT
A
(A
)-
GN
D
D
AT
A
(B
)+
D
AT
A
(A
)-
GN
D
D
AT
A
(B
)+
D
AT
A
(A
)-
GN
D
C01415-1-1