Micro Motion Fisher-Rosemount RFT9709, Instruction Manual

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RFT9709 Transmitter Instruction Manual
21
Wiring
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Frequency/pulse output The frequency/pulse output represents mass, mass flow rate, gross
volume, gross volume flow rate, gross standard volume, or gross
standard volume flow rate, independent of the mA outputs.
Figure 2-13.
Frequency/pulse output
terminals
Output performance and requirements
• 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.
• 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 output-voltage and
electrical-current ratings of the RFT9709.
• RFT9709 output is a n23 V square wave, unloaded. Any load
will decrease the peak voltage level.
• Output impedance is 3.3 kohm.
• The frequency/pulse output loop is isolated and floating. Additional
grounding will result in optimum performance. Ensure that the
frequency/pulse output loop is grounded at the external device.
• If necessary, the frequency output can be configured for open collector
mode. For instructions, see Appendix D, page 53. When used in the
open collector mode, the output circuit is rated to 30 VDC, with 0.1
ampere maximum sinking capability.
Output fault setting
The frequency/pulse output can be set to produce downscale or upscale
fault levels.
• If set to downscale (switch 7 off), a fault drives the output to 0 Hz
• If set to upscale (switch 7 on), a fault drives the outputs to 15-19 kHz
Low-flow cutoff
Flow values below the user-defined low-flow cutoff cause the output to
default to the level that represents zero flow.
RFT9709 terminals
for output wiring
11 1
2
13
14 15
16
17
18
19
20 2
1
22
FREQ (signal line)
F GND (return)
Terminal 18 is a common return for the frequency/pulse
output, the control output, and the external zero input.
09wire.fm Page 21 Monday, March 1, 1999 4:31 PM