Instruction manual

28 RFT9739 Field-Mount Transmitter Instruction Manual
Output Wiring
continued
Use RFT9739 terminals 17 and 18 for the primary mA output. Use
terminals 19 and 20 for the secondary mA output. See
Figure 5-3
.
• Primary and secondary mA output loops are isolated and floating.
Additional grounding will result in optimum performance, and optimum
HART communication on the primary mA output. Ensure that mA
output loops are grounded properly, either at the transmitter end, or at
the external device.
• The maximum allowable length for mA signal wiring is determined by
measuring resistance over the signal wires and through the receiver
device. Total loop resistance must not exceed 1000 ohms.
• The primary mA output must be set to the 4-20 mA mode for the Bell
202 physical layer. The Bell 202 layer will not work with the primary mA
output configured as a 0-20 mA output.
• The mA output cannot be converted from active to passive.
Figure 5-3. Primary and secondary mA output wiring
PV+ (signal line)
PV– (return)
SV+ (signal line)
SV– (return)
RFT9739
output terminals
PV = Primary variable
SV = Secondary variable