Instruction manual

Output Wiring
continued
RFT9739 Rack-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 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 information about using AMS software, see 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.
Rack-mount
RFT9739
HART socket
(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
PV+
PV–
HART socket or
PV terminals