JPS64854B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a retransmission pulse generator that scales an input pulse and then outputs it as a retransmission pulse.

Generally, in a pulse generation flowmeter such as a turbine flowmeter, the number of pulses per unit volume of passing fluid is not a well-defined value, such as 12.42 pulses per unit volume. For this reason, when calculating the cumulative flow rate, the input pulses from the pulse emitting type flowmeter are scaled and converted into unit pulses, such as 10 pulses per pulse, and then retransmitted. In this case, conventionally, the input pulses are thinned out to be as close to equal intervals (fixed period) as possible according to the principle determined for a given scaling constant K (for example, 10/12.42), so that the input pulses are When a signal is input, it outputs 805 retransmission pulses. In this way, in the past, the signals were simply thinned out so that the intervals were close to equal, so accurate equidistantness was not maintained, resulting in a signal containing ripples, so to speak. The ripple becomes larger as the frequency becomes lower. Therefore, when the retransmitted pulse was used as a demand pulse (set value) of the mixing controller, the ripple of the control output was large and the stability was poor.

SUMMARY OF THE INVENTION An object of the present invention is to realize a retransmission pulse generator that can continuously generate retransmission pulses with excellent uniform intervals.

The present invention counts input pulses with an input counter, reads this counted value every measurement period, multiplies it by a scale constant to obtain the number of retransmission pulses, and multiplies the input pulse period by the reciprocal of the scale constant to generate a reference retransmission pulse. Calculate the period, multiply the reciprocal of this standard retransmission pulse period by the preset retransmission pulse activation period to obtain the standard retransmission pulse number, and the number of retransmission pulses set in the retransmission pulse output circuit is the standard retransmission pulse. By controlling the retransmission pulse period so that the retransmission pulse period becomes a value obtained by multiplying the number by a coefficient, a retransmission pulse generator that can achieve the above-mentioned object is realized.

FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention. In the figure, 1 is an input counter that counts input pulses Pi, 2 is a retransmission pulse number calculation circuit, 3 is a buffer register, 4 is an input pulse period detection circuit, 5 is a reference retransmission pulse period calculation circuit,
6 is a reference retransmission pulse number calculation circuit, 7 is a setting circuit, 8 is a normalization circuit, and 9 is a PI calculation circuit, which is composed of a PI calculation section ΔPI and an addition section Σ and performs speed type PI calculation. ing. 10 is a re-transmission pulse period calculation circuit; 11 is a re-transmission pulse output circuit;
When the pulse period and number of pulses are set, the retransmission pulse Po is outputted by the set number of retransmission pulses Po at the set period, and when the output is finished, a retransmission pulse end signal Pe is generated.

The operation of the apparatus of the present invention constructed as described above will be explained below using the time chart shown in FIG. Second
In the figure, A is a time chart under normal conditions, and B is a time chart when the cycle becomes too fast. First, retransmission pulse number calculation circuit 2
reads the count value of input counter 1 every measurement period Δt, multiplies it by the scale constant K, and calculates the number of retransmitted pulses Ni
Output. This number of retransmission pulses Ni is added by the buffer register 3. On the other hand, the input pulse period detection circuit 4 detects the period Ti of the input pulse Pi from the count value of the input counter 1 for each measurement period and supplies it to the reference retransmission pulse period calculation circuit 5.
is multiplied by the reciprocal of the scale constant 1/K to calculate the reference retransmission pulse period Ts. The value is updated every measurement cycle. This reference re-transmission pulse period
Ts is added to the reference retransmission pulse number calculation circuit 6,
The standard number of retransmission pulses Ns is output by multiplying the reciprocal of Ts by a preset retransmission pulse activation period (for example, the same period as the measurement period) Ta. This reference number of retransmission pulses Ns is added to the setting circuit 7, multiplied by a preset coefficient n, and a set value SV is output. Here, the reason why the coefficient n is multiplied is that the SV has a phase delay, and by providing a reservoir in the buffer register 3, the waiting time when the cycle becomes too fast as shown in FIG. This is to prevent output ripple caused by TL from appearing in a stable state. Note that as n increases, the phase delay increases, so in this embodiment, n=2, the SV is delayed by one cycle, and the buffer register 3 is provided with a reservoir for one cycle. The difference between this set value SV and the content N of the buffer register 3, which is the measured value PV, is added to the normalization circuit 8, and after performing the normalization calculation e _o = nNs - N/Ns (1), PI It is added to the arithmetic circuit 9. The PI calculation circuit 9 is the output e _o of the normalization circuit 8.
Then, with the proportional gain as Kp and the integration time as K _I , the calculation section ΔPI performs the calculation Δα = Kp {(e _o − e _o ― ₁ ) + K _I e _o } (2), and as a result, Δα is added. part Σ and performs velocity-type PI calculations. By the way, the SV value
The difference between nNs and PV value N is normalized in the normalization circuit 8 and then added to the PI calculation extension circuit 9 as follows.
This is to prevent Δα from changing depending on the frequency. The output α of the PI calculation circuit 9 is given to the retransmission pulse period calculation circuit 10, and the calculation Tj=Ts(1−α) (3) is performed between it and the reference retransmission pulse period Ts, and the retransmission pulse A period Tj is calculated. That is, α of the retransmission pulse period Tj is controlled such that the number of retransmission pulses becomes the reference number of retransmission pulses Ns. This retransmission pulse period Tj and the number of retransmission pulses Nj from the buffer register 3 are set in the retransmission pulse output circuit 11 in synchronization with the retransmission pulse end signal Pe. At this time, the number of retransmission pulses Nj from the buffer register 3 is set by comparing the number of retransmission pulses N stored in the buffer register 3 with the reference number of retransmission pulses Ns.
If NNs, Nj=N, if N>Ns
Nj=Ns. When the retransmission pulse output circuit 11 finishes outputting a set number of retransmission pulses Po at a set period, it outputs a retransmission pulse end signal.
Output Pe. The retransmission pulse end signal Pe is given to the buffer register 3 and the retransmission pulse period calculation circuit 10, and the retransmission pulse output circuit 11 is set to the period Tj and the number of pulses Nj of the retransmission pulse to be output next. The retransmission pulse Po continues to be generated while changing the pulse period continuously according to the procedure. Specifically, as shown in Fig. 2A, after the processing of the lth sampled input pulse Pi is completed, the retransmission end for the l-1st input pulse is controlled to occur in the l+1st period. .

Also, since the maximum value of the number of retransmitted pulses at one time is set to Ns, even if the number of input pulses increases rapidly and the content N of the buffer register 3 temporarily increases,
It is possible to end the re-transmission in a short cycle, shorten the cycle each time, and send out the excessively large amount quickly. If the maximum number of pulses to be retransmitted at one time is not limited, if the contents of buffer register 3 become large, the cycle cannot be changed until that many pulses have been output, and too many pulses will be exposed. it takes time.

As explained above, in the present invention, the number of reference retransmission pulses is calculated based on the reference retransmission pulse period calculated from the input pulse period and the reciprocal of the scale constant, and the preset retransmission pulse activation period. is calculated, and the retransmission pulse period is controlled so that the number of retransmission pulses obtained from the number of input pulses and the scale constant becomes the reference retransmission pulse number, so retransmission pulses with excellent uniformity can be generated. A retransmission pulse generator is obtained which can generate continuous pulses.

In addition, the retransmission pulse number calculation circuit 2, the buffer register 3, the input pulse period detection circuit 4, the reference retransmission pulse period calculation circuit 5, the reference retransmission pulse number calculation circuit 6, and the settings are surrounded by a dashed line in FIG. A microcomputer may be used as the circuit 7, the normalization circuit 8, the PI calculation circuit 9, and the retransmission pulse period calculation circuit 10, and these functions may be realized by a software program. In this case, the retransmission pulse end signal from the retransmission pulse output circuit 11
Pe will interrupt the microcomputer.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention, and FIG. 2 is a time chart for explaining its operation. DESCRIPTION OF SYMBOLS 1...Input counter, 2...Retransmission pulse number calculation circuit, 3...Buffer register, 4...Input pulse period detection circuit, 5...Reference retransmission pulse period calculation circuit,
6... Reference re-transmission pulse number calculation circuit, 7... Setting circuit, 8... Normalization circuit, 9... PI calculation circuit, 10...
Retransmission pulse period calculation circuit, 11...Retransmission pulse period calculation circuit.

Claims (1)

[Claims] 1. An input counter that counts input pulses, a retransmission pulse number calculation circuit that calculates the number of retransmission pulses by reading the count value of this input counter every measurement cycle and multiplying it by a scale constant, and this retransmission pulse number calculation circuit. A buffer register that adds the output, and a period detection method that reads the count value of the input counter every measurement period, calculates the input pulse period, and obtains the reference retransmission pulse period by multiplying this input pulse period by the reciprocal of the scale constant. circuit, a reference retransmission pulse number calculation circuit that obtains a reference retransmission pulse number from this reference retransmission pulse period and a predetermined retransmission pulse starting period, and a reference retransmission pulse number calculation circuit that calculates a reference retransmission pulse number by a preset coefficient. A PI calculation is performed in the PI calculation circuit using the value as the set value and the content of the buffer register as the measurement value, and retransmission is performed so that the content of the buffer register becomes the value obtained by multiplying the reference retransmission pulse number by a coefficient. means for controlling a pulse period; and a retransmission pulse output for outputting retransmission pulses with the retransmission pulse period set and a retransmission pulse number set from the contents of the buffer register and the reference retransmission pulse number. A retransmission pulse generator having a circuit.