Dwyer UXF3 - Manual (Page 47)

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4.9.2. Setting the total
4.9.2.1. Setting the total pulse (pulse value, pulse width)
Description
z Set to totalize a process variable (flow rate) by total meter, etc. according to total pulse output.
z Pulse value: Total amount (volume) per pulse.
A pulse is outputted when the total volume has attained an amount set by the pulse value, and adds to the total pulse count (in case of
total pulse indication). Settable range: 0.000001 to 99999999
* Set the total unit before setting the pulse value. (See Section 4.8.3.)
z Pulse width: Width of total pulse output.
Select a pulse width according to a corresponding total meter out of menus. Settable range: 5ms, 10ms, 50ms, 100ms, 200ms
Note) If the output is through DO2 (relay contact), select 50ms or longer. (See Section 4.9.3.)
z Restrictions in the setup
Output of total pulses involves the following restrictions depending on the DO output port (DO1, DO2, DO3).
DO output port Frequency range of pulse output
(at full scale flow rate) Pulse width
DO1, DO2: Transistor, open collector 100 pulse/sec 5ms, 10ms, 50ms, 100ms, 200ms
DO3: Relay contact 1 pulse/sec 50ms, 100ms, 200ms
The maximum output frequency is also restricted by the setup of the pulse width. Therefore, set the pulse width and pulse value so
that both of condition 1 and condition 2 indicated below are satisfied. Correct results may not occur, if any setup that does not satisfy
both of condition 1 and condition 2 is made.
Condition 1:
FULL SCALE ( Note1) [m 3 /s]
TOTAL RATE [m 3 ]
d
100[Hz]
1[Hz]
(In case of DO1, DO2)
(In case of DO3)
Condition 2:
FULL SCALE ( Note1) [m 3 /s]
TOTAL RATE [m 3 ]
d
1000
2 × PULSE WIDTH [ms]
Note 1) The range of FULL SCALE1 or FULL SCALE2, whichever is larger, is the object in the case of automatic 2-range setup,
forward and reverse range setup or forward and reverse automatic 2-range setup.
Note 2) The output frequency on the output ports is limited when the flow rate exceeds the set range. Therefore, if such a setup that
the maximum frequency per range occurs at the time of 100% flow rate, there is possibility that the total pulse output will be
incapable of following when the flow rate exceeds 100%, and accurate total value cannot be obtained if over-range continues
for a long time. If there are cases where the flow rate exceeds 100%, modify the set range and pulse value so that the
maximum frequency will not exceed the restricted level.
Example of calculation
Calculate the range that permits setup of the total value under the range and pulse width indicated below.
When the range and the pulse width are as follows.
FLOW SPAN -1: 36[m
3 /h] (=0.01[m 3 /s]), Pulse width:50[ms]
i) In case of DO1/DO2 output
Condition 1
TOTAL RATE t
FULL SCALE [m 3 /s]
100[Hz]
=
0.01 [m 3 /s]
100 [Hz]
= 0.0001 [m 3 ] = 0.1 [L]
As above:
0.1 [L] d TOTAL RATE ·································································································································· A
Condition 2
TOTAL RATE t FULL SCALE [m 3 /s] ×
2 ˜ PULSE WIDTH [ms]
1000
= 0.01 [m 3 /s] ×
2 ˜ 50 [ms]
1000
= 0.001 [m 3 ] = 1 [L] ····························· B
The settable range of the total value that satisfies both of condition 1 and condition 2 is as follows from results of calculation A and B.
1 [L] d TOTAL RATE
ii) In case of DO3 output
Condition 1
TOTAL RATE t
FULL SCALE [m 3 /s]
1 [Hz]
=
0.01 [m 3 /s]
1 [Hz]
= 0.01 [m 3 ] = 10 [L] ········································································ C
Condition 2 is same as that of the case of DO1 output indicated above.
Therefore, the settable range of the total value is as follows from results of calculation B and C.
10 [L] d PULSE VALUE d 864 [m 3 ]
Note) When the total setting value is “0”, total pulse is not output.
Note) When setting, stop status is set at the total mode.
For actual keying, refer to the typical operation indicated below. Set the parameter protection to OFF beforehand. (See Section 4.4.1.)
Bulletin F-107-UXF3