DigitalFlow™ DF868 Multipurpose Ultrasonic Liquid Flowmeter Programming Manual (2-Channel) 23
Chapter 1. Programming Site Data
TransFlection SIGNL Options
1. Press [ENT] to accept the current Signal Low Limit value or enter a new value and press [ENT].
The default value for this parameter is 40 and values from –20 to 100 are acceptable. The E1: LOW SIGNAL error
message appears when the signal strength falls below the programmed Signal Low Limit value. See the Service
Manual for a discussion of error codes.
2. Press [ENT] to accept the current Velocity Low Limit value or enter a new value and press [ENT].
The default value for this parameter is –40.0 ft/sec (–12.142 m/sec) and values from –100 to 100 ft/sec (–30.48 to
30.48 m/sec) are acceptable. The E3: VELOCITY RANGE error message appears when the calculated fluid velocity is
less than the programmed Velocity Low Limit value. See the Service Manual for a discussion of error codes.)
3. Press [ENT] to accept the current Velocity High Limit value or enter a new value and press [ENT].
The default value for this parameter is –40.0 ft/sec (–12.142 m/sec) and values from –100 to 100 ft/sec (–30.48 to
30.48 m/sec) are acceptable. The E3: VELOCITY RANGE error message appears when the calculated fluid velocity
exceeds the programmed Velocity High Limit value. See the Service Manual for a discussion of error codes.
4. Press [ENT] to accept the current Gain Setting, or press [F1] to lower the received signal or [F2] to boost the
received signal.
The Gain Setting option lets you select either low or high (default) gain for the selected channel. The gain setting
either boosts or lowers the received signals. Normally the gain setting is HIGH; however, if the signal is virtually
noise-free, the gain setting can be switched to LOW.
5. At the Flow Direction prompt, press [F1] to specify absolute flow velocity, [F2], UP (for upstream) if the
transducers face against the flow, or [F3], DOWN (for downstream), if the transducers face with the flow.
Use this option to specify the direction in which the fluid is flowing. While the DF868 normally measures the absolute
value of the flow velocity, you can specify in which direction the transducers face by selecting UP or DOWN.
Note: Selecting UP or DOWN cuts the TransFlection measurement range in half from 1 to 30 ft/s (0.3 to 9 m/s) to -15
to +15 ft/s (-4.6 to +4.6 m/s).
6. Press [ENT] to accept the current Rep Period 1 value, or use the [F1]-[F4] keys and [
and [ keys to select the
desired value (from 100 to 3200).
7. Press [ENT] to accept the current Rep Period 2 value, or use the [F1]-[F4] keys and [
and [ keys to select the
desired value (from 100 to 3200).
Use these two options to set the minimum and maximum time interval between transmissions. Increasing the
repetition period reduces the amount of background noise in the signal at the expense of reducing the maximum
measurable flow rate. Since the DF868 adjusts repetition periods to optimize the flow measurement (taking flow rate,
transducer frequency, and signal characteristics into consideration), you must enter a range, from 100 to 3200 µsecs.
REP PERIOD 1 specifies the shortest repetition period possible, with a default of 200 µsec. REP PERIOD 2 specifies the
longest repetition period the DF868 can use, and defaults to a value of 800 µsec.
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