dynasonics TFX Ultra - Channel 1 Menu (CH1)

Channel 1 Menu (CH1)
The CH1 menu controls how the 4-20 mA output is spanned for all transmitter models and how the frequency output is
spanned for the flow-only model.
Parameter Meaning Description
FL 4MA Flow at 4 mA The FL 4MA and FL 20MA settings are used to set the span for both the 4-20 mA output and the 0…1000 Hz
frequency output on the Flow-Only models.
The 4-20 mA output is internally powered (current sourcing) and can span negative to positive flow/energy rates.
This output interfaces with virtually all recording and logging systems by transmitting an analog current that is
proportional to system flow rate. Independent 4 mA and 20 mA span settings are established in firmware using
the flow measuring range entries. These entries can be set anywhere in the –40…40 fps (–12…12 mps) range
of the instrument. Resolution of the output is 12-bits (4096 discrete points) and the can drive up to a 400 Ohm
load when the transmitter is AC powered. When powered by a DC supply, the load is limited by the input voltage
supplied to the instrument. See Figure 24 for allowable loop loads.
FL 4MA — Flow at 4 mA
FL 20MA — Flow at 20 mA
The FL 4MA and FL 20MA entries are used to set the span of the 4-20 mA analog output and the frequency output
on Flow-Only models. These entries are volumetric rate units that are equal to the volumetric units configured as
RATE UNT and RATE INT discussed previously.
For example, to span the 4-20 mA output from –100…100 gpm, with 12 mA being 0 gpm, set the FL 4MA and FL
20MA inputs as follows:
FL 4MA = –100.0
FL 20MA = 100.0
If the transmitter were a Flow-Only model, this setting would also set the span for the frequency output. At –100
gpm, the output frequency would be 0 Hz. At the maximum flow of 100 gpm, the output frequency would be
1000 Hz, and in this instance a flow of zero would be represented by an output frequency of 500 Hz.
Example 2 – To span the 4-20 mA output from 0…100 gpm, with 12 mA being 50 gpm, set the FL 4MA and FL
20MA inputs as follows:
FL 4MA = 0.0
FL 20MA = 100.0
For the Flow-Only model, in this instance zero flow would be represented by 0 Hz and 4 mA. The full scale flow or
100 gpm would be 1000 Hz and 20 mA, and a midrange flow of 50 gpm would be expressed as 500 Hz and 12 mA.
FL 20MA Flow at 20 mA
CAL 4MA 4 mA calibration The 4-20 mA output is factory calibrated and should not require adjustment. If small adjustments to the DAC
(Digital to Analog Converter) are needed, for instance if adjustment due to the accumulation of line losses from
long output cable lengths are required, the CAL 4mA and CAL 20 MA can be used.
CAL 4 MA — 4 mA DAC Calibration Entry (Value)
CAL 20 MA— 20 mA DAC Calibration Entry (Value)
The CAL 4MA and CAL 20 MA entries allow fine adjustments to be made to the zero and full scale of the 4-20
mA output. To adjust the outputs, an ammeter or reliable reference connection to the 4-20 mA output must
be present.
OTE:N Calibration of the 20 mA setting is conducted much the same way as the 4 mA adjustments.
OTE:N The CAL 4MA and CAL 20MA entries should not be used in an attempt to set the 4-20 mA range. Use
FL 4MA and FL 20MA, detailed above, for this purpose.
CAL 20 MA 20 mA calibration
4-20 TST 4-20 mA test Allows a simulated flow value to be sent from the 4-20 mA output. By incrementing this value, the 4-20 mA
output will transmit the indicated current value.
4 mA Calibration Procedure
1. Disconnect one side of the current loop and connect the ammeter in series (disconnect either wire at the terminals
labeled 4-20 mA Out or Signal Gnd).
2. Using the arrow keys, increase the numerical value to increase the current in the loop to 4 mA. Decrease the value to
decrease the current in the loop to 4 mA. Typical values range between 40…80 counts.
3. Reconnect the 4-20 mA output circuitry as required.
Conguration
Page 41 May 2016 TTM-UM-00136-EN-06