Instruction manual

Output Wiring
continued
RFT9739 Field-Mount Transmitter Instruction Manual 29
Output Wiring Startup TroubleshootingBefore You Begin Getting Started Mounting
Power-Supply and
Sensor Wiring
Connections for HART
®
communication devices
Figure 5-4
illustrates how to connect a HART Communicator, the
ProLink PC-Interface adaptor, or an AMS serial modem to the RFT9739
for digital communication over the primary mA output. For information
about using the HART Communicator or ProLink program, see the
appropriate instruction manual. For AMS software, use the AMS on-line
help:
Figure 5-4. HART
®
Communicator, ProLink
®
PC-Interface, and AMS modem connections
1. If necessary, add resistance in the loop by installing resistor R1. SMART FAMILY
®
devices require a minimum loop
resistance of 250 ohms. Loop resistance must not exceed 1000 ohms, regardless of the communication setup.
2. The DCS or PLC must be configured for an active milliamp signal.
3. Resistor R3 is required if the DCS or PLC does not have an internal resistor.
CAUTION
Connecting a HART device to the RFT9739 primary variable milliamp output loop could cause transmitter
output error.
If the primary variable (PV) analog output is being used for flow control, connecting a HART device to the output
loop could cause the transmitter 4-20 mA output to change, which would affect flow control devices.
Set control devices for manual operation before connecting a HART device to the RFT9739 primary variable
milliamp output loop.
Field-mount
RFT9739
PV terminals
17 and 18
Communicator loops
(same circuit as
PV terminals)
R2
R3
(Note 3)
R1
(Note 1)
DCS or PLC
with internal
resistor
(Note 2)
HART
Communicator,
ProLink PCI,
or AMS modem
Communicator loops
or PV terminals
PV+
PV–