Instruction manual

30 RFT9739 Field-Mount Transmitter Instruction Manual
Output Wiring
continued
5.4 Frequency/pulse output
The RFT9739 frequency/pulse output represents the flow rate or flow
total, independent of the primary and secondary mA outputs. The
frequency/pulse output can be used with any Micro Motion peripheral
device except the DMS Density Monitoring System and the PI 4-20
Process Indicator, which do not have frequency inputs.
The frequency/pulse output can be configured to provide any one of the
following:
• Mass flow rate
• Volume flow rate
• Mass flow total
• Volume flow total
Mass flow total and volume flow total are not available with some
RFT9739 transmitters shipped prior to 1998.
Use RFT9739 terminals 15 and 16 for the frequency/pulse output. The
frequency/pulse output, control output, and external zero input share
terminal 16 as a common return. See
Figure 5-5
, page 31.
• The frequency/pulse output loop is isolated and floating from other
circuits except the control output and external-zero input circuits.
Ensure that the frequency/pulse output loop is grounded properly,
either at the transmitter end, or at the external device.
• The frequency output circuit uses a 2.2 kohm resistor tied to a 15-volt
source that limits the current to 7 mA. The output circuit is rated to 30
VDC, with 0.1 ampere maximum sinking capability, when used in the
open collector mode. Open collector mode is described on page 33.
• Transmitter output is a nominal +15 V square wave, unloaded. Any load
will decrease the peak voltage level.
• Output impedance is 2.2 kohm.
• For use with receivers other than Micro Motion peripheral devices,
check the instruction manual for the receiver to make sure its input-
voltage and electrical-current ratings match the RFT9739
frequency/pulse output ratings.