Dynasonics TFX Ultra Transit Time Flow Meters - Manual (Page 47)

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 unit, 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.
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. Utilize FL 4MA and
FL 20MA, detailed above, for this purpose.
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.
20 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 20 mA. Decrease the value to
decrease the current in the loop to 20 mA. Typical values range between 3700…3900 counts.
3. Reconnect the 4-20 mA output circuitry as required.
4-20 TST — 4-20 mA Output Test (Value)
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.
CH2 Menu — Channel 2 Menu
The CH2 menu is used to configure model specific I/O options. The flow only unit presents a different set of parameters than
the energy meter.
IT IS POSSIBLE TO CHOOSE OPTIONS PERTAINING ONLY TO THE FLOW ONLY METER WHEN AN ENERGY METER IS
PRESENT. THE OPPOSITE IS ALSO TRUE. THE PROPER MENU TYPE MUST BE CHOSEN FOR THE ACTUAL METER. IF THIS
CAUTION ISN’T FOLLOWED, THE OUTPUTS OR METER READINGS WILL BE UNPREDICTABLE.
Channel 2 Options
CH2 Menu — Channel 2 I/O Options (Choice)
RTD — Input Values for Energy Meters (Values)
CONTROL/HZ — Output Options for Flow Only Meters
BSC MENU – BASIC MENU
Page 47 March 2014