JPH0318239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-point data measuring device having disconnection detection means for a signal source under test, and by improving the disconnection detection sequence, it is possible to measure multi-point data at high speed. This is how it was done.

There are two methods of measurement sequences shown in FIG. 1A and 1B in a multi-point data measurement apparatus having a means for detecting disconnection of the signal source under test. The sequence (a) is a sequence in which disconnection is detected for each channel (CH) immediately before measurement, and the sequence (b) is a sequence in which disconnection is checked for all channels prior to measurement.
This method then runs the measurement sequence for all channels.

However, in method A, measurement is performed immediately after detecting a disconnection, so if a measuring device has an input section that takes a long time to recover from the effects of detecting a disconnection, a measurement error will occur if high-speed data processing is attempted. Also,
The method (B) has the drawback that the waiting time from the start of measurement ts to the start of measurement is long, and significant data may be missed.

The present invention has been made to improve these points, and the measurement sequence thereof is shown in FIG. As shown in Figure 2, in the present invention, the measurement starts
First, all channels are measured from ts, and disconnections in all channels are detected after the measurement is completed.

In the multi-point data measuring device of the present invention having such a sequence, the disconnection check for all channels is performed at once after the measurement of all channels, so even if it takes time for the effects of the disconnection check to recover. Even in the case of a multi-point data measuring device having a long input section, the time required for recovery can be substantially ignored, and multi-point data can be measured with high accuracy in a short time. Furthermore, since measurement begins immediately after the start of measurement, there is no possibility of missing significant data.

Although the input circuit used in the multi-point data measuring device of the present invention is not necessarily limited to a specific one, the input section used in the embodiment and the configuration of the multi-point data measuring device having this input section will be explained below. The insulation circuit used in this input section has already been filed as Japanese Patent Application No. 107511/1983 by the applicant of the present invention. Hereinafter, before explaining the multi-point data measuring device of the present invention, the insulation circuit of the previously applied application will be explained using FIG. 3.

In Figure 3, E _X is the signal source to be measured, Dp is a diode circuit in which diodes _D1 and _D2 are connected in parallel and with opposite polarity, and the characteristics of current I with respect to voltage V are shown in Figure 4. . Similarly, Ds is a diode circuit in which diodes D ₃ and D ₄ are connected in parallel and with opposite polarity, and its V and I characteristics are similarly 4th.
Illustrated in the figure. T is a 1:1 small pulse transformer having a tertiary winding n ₃ , and an impulse current i ₀ is supplied to this tertiary winding n ₃ . C ₁ and C ₂ are capacitors, and a diode circuit is connected in anti-parallel with capacitor C ₁
An input circuit is composed of Dp and the primary winding n ₁ of the transformer T, and an output circuit is composed of the secondary winding n ₂ of the transformer T, the anti-parallel connected diode circuit Ds, and the capacitor C ₂ . If the transformer T is an ideal transformer, the voltages e 1 and _{e 2} generated in the primary and secondary windings n ₁ and n _{2 are}
And for the currents i ₁ and i 2 flowing through _the windings n ₁ and n ₂ , e ₁ = e ₂ , i ₁
If the relationship +i ₂ =i ₀ is established, and further considering the left-right symmetry seen from the transformer T, then i ₁ =i ₂ =i ₀ /2 in the steady state. Assuming the impulse current i ₀ supplied to the tertiary winding n ₃ , the amplitude shown in Figure 5 A is ±I ₀
If the currents are used, i ₁ and i ₂ become pulse currents with an amplitude of ±I ₀ /2 as shown in FIG. 3B.

In the V and _I characteristics _{of the} diodes D ₁ , D ₂ (D ₃ , D ₄ ) shown in FIG _. , Δ′ ₁ , Δ′ ₂ ) for Δ ₄ , the voltage e ₁ generated in the primary winding n ₁ of the transformer T is ( _EX + Δ ₁ ) when the impulse current i ₀ is a positive pulse. , when i ₀ is a negative pulse, ( _E
Δ ₂ ). Similarly, the voltage e ₂ in winding n ₂ of the output circuit
As shown in Figure 3C, when i ₀ is a positive pulse, e ₂ =
E ₂ +Δ′ ₁ , and e ₂ =E ₂ +Δ′ ₂ during negative pulse. Voltage
e ₂ is waveformed by capacitor C ₂ and becomes the output voltage E ₂ . This output voltage E ₂ is balanced at a value that satisfies e ₁ =e ₂ . In other words, the output voltage E ₂ is expressed _{by the following two equations: When i 0 is a positive pulse...E X +Δ 1 = E 2 + Δ ' 1 When i 0 is a} negative pulse...E It is derived as the additive average value of .

_{E 2 = E _ _ _ _ _ _ 2}
is equal to the input DC voltage _EX and is electrically isolated from the input circuit. In addition, although the case where the tertiary winding _n3 is used in the transformer T is illustrated above, as shown in Fig. 6A, the impulse current source IP is the primary winding,
Secondary winding n 2 of a transformer T with secondary windings n _{1 ,} n ₂
Alternatively, it may be connected between both ends of the parallel diode circuits Dp and Ds. In addition, diodes D ₁ , D ₂ (D ₃ ,
D ₄ ) may be replaced with a diode-connected transistor as shown in FIG. 6B.

Such an insulating circuit has a simple circuit configuration and can insulate low-level signals despite its small size, and is currently used in a variety of applications.

The present invention is a measuring device having such an insulating circuit at its input section, in which the measurement sequence is improved as explained in FIG. 2, and an embodiment thereof is shown in FIG. In Fig. 7, IS ₁ , IS ₂ , ... are the insulation circuits shown in Fig. 3, _EX1 , _EX2 , ... are the signals under test, and R _X1 , R _X2 , ... are the signals under test, respectively. It shows the impedance of the source. Thermocouples are often used as this signal source. ρ ₁ and ρ ₂ are insulation resistances specific to the mounted components, S ₁ , S ₂ , ... are respectively scanner switches, A is an amplifier, AD is an analog-to-digital converter (hereinafter simply referred to as AD converter), and CONT is The arithmetic control circuit, DIS is a display circuit, SB is a disconnection detection switch, IBS is a current source for disconnection detection, COP is a comparator, and ES is a reference voltage source. The insulation resistance ρ ₁ is connected in parallel with the capacitor C ₁ , and the signal source under _{test E}
are connected in parallel. The insulation resistance ρ ₂ is connected in parallel to the capacitor C ₂ , and one of its connection _points is connected to the display circuit DIS through. The input terminal of the amplifier A is further connected to a current source IBS via a switch SB, and is also connected to one input terminal of a comparator COP. In addition,
One input terminal of the comparator COP may be connected to the output terminal of the amplifier A, as shown by the dotted line in the figure.
The other input terminal of the comparator COP is the reference voltage source
Connected to common via ES. The output end of the comparator COP is connected to the arithmetic/control circuit CONT. The insulating circuits IS ₂ , . . . also have exactly the same configuration as the above-mentioned insulating circuit IS ₁ , and the switches S ₂ , . . .
... are connected to the input terminal of amplifier A, respectively.

The operation for detecting a disconnection in the apparatus of the present invention having such a configuration will be explained as follows.
This disconnection detection is performed after measuring the signals under test _EX1 , _EX2, . . . as shown in the sequence of FIG. Measurement of signals to be measured _EX1 , _EX2 , ... is done using scanner contacts.
Isolation circuits IS ₁ , IS 2 , ... which turn on S 1 and S ₂ sequentially and operate _{E X1} , E _X2 , ... based on the explanation in Fig. 3 _are constructed.
... to an AD converter, and the AD converter sequentially converts the input signals _EX1 , _EX2 , ... into digital signals, which are then input to the arithmetic/control circuit CONT. After measuring all channels,
Next, a disconnection detection sequence begins. Even after detecting a disconnection, the scanner contacts S ₁ , S ₂ , . . . are turned on in sequence. Now, when the scanner contact _S1 is on and the disconnection detection switch SB is turned on at time _t0 shown in Figure 8, the disconnection detection current IB obtained from the current source IBS is isolated via the switch SB and _S1 . circuit IS ₁
The current flows to the output side capacitor C ₂ at the output side, thereby charging C ₂ . Almost simultaneously with this charging, the potential is transferred to the capacitor C ₁ of the input circuit. As a result, the voltage e _i of the capacitor C ₁ is shown as curve A in FIG. Next, in FIG. 8, switch SB is turned off at time _t1 , and the operation in this case will be discussed. Now, the signal source under test _E
When the impedance R _X1 of is small, the charge in the input circuit side capacitor C ₁ is discharged with a time constant of C ₁ ·R _X1 , so its potential drops rapidly. isolated circuit
IS, the output voltage _eO also decreases almost simultaneously following the potential of capacitor _C1 . This situation is shown by curve B in FIG. On the _other hand _, if _{the impedance R X1 of the signal} source to be measured E It decays slowly. Therefore, if the value of the reference voltage Es used for the comparator COP is set to Ec, then at a certain time (for example, time t ₃ ) after the switch SB is turned off, the comparison level Ec will become a curve B. The curves are clearly separated and this difference is explained by the comparator
Detected by COP. That is, a disconnection of the signal source under test _EX1 can be detected by the comparator COP. Disconnection of _the signal source under test _E
The operations are performed sequentially according to the above operations. comparator
The output of COP is input to the arithmetic/control circuit CONT. Using the signal obtained by the comparator COP, the arithmetic/control circuit CONT determines whether the values of the previously input signals under test _EX1 , _EX2 , . . . are significant or insignificant. The display circuit DIS displays or prints the significant value of the signal to be measured obtained from the control circuit CONT as measurement data.

In this way, in a device that has capacitors C ₁ and C ₂ in the input section and detects the presence or absence of a wire break in the signal source under test by flowing the disconnection detection current IB through these, the capacitors C ₁ and C Measuring the _2nd charge before it is completely discharged will cause an error, but it takes a considerable amount of time for it to be completely discharged. Therefore, as shown in FIG. 1A, in a sequence in which disconnection is detected and measured for each channel, when the number of channels increases, a considerable amount of time is required to measure all channels. In addition, even if all channels are disconnected prior to measurement as shown in Figure 1B, in a device that detects the presence or absence of disconnection by flowing a disconnection detection current through capacitors C1 and C2, the capacitor Since it takes a considerable amount of time for the discharge to occur, data on presence or absence may be lost. On the other hand, since the apparatus of the present invention detects disconnection all at once, it can perform this detection at a higher speed than the apparatus shown in FIG. 1A. Moreover, since disconnection detection is performed after the measurement of all channels is completed, measurement starts immediately after the measurement command, so there is no possibility of missing significant data as in the apparatus shown in FIG. 1B.

[Brief explanation of the drawing]

Figures 1A and 1B are diagrams for explaining the conventional measurement sequence, Figure 2 is a diagram for explaining the measurement sequence of the device of the present invention, and Figure 3 is a diagram of the isolation circuit used in the measurement device of the present invention. Connection diagrams, FIGS. 4 and 5 are diagrams for explaining the characteristics and operation of FIG. 3, FIG. 6 is a diagram showing another circuit example of FIG. 3, and FIG. 7 is a measuring device of the present invention. FIG. 8 is a connection diagram showing one embodiment of the present invention, and is a diagram for explaining its operation. IS ₁ , _{IS 2} , ...Isolation circuit, _EX1 , E

Claims (1)

[Claims] 1. A pulse transformer whose tertiary winding is supplied with an impulse current, and a pair of diodes each connected in parallel and in opposite directions, and a diode circuit and each diode connected separately to the first and second windings of the pulse transformer. A plurality of insulating circuits having the same configuration each including a capacitor connected to the primary and secondary windings of the pulse transformer through a circuit and having a signal source to be measured connected to the primary winding; An analog-to-digital converter to which the secondary winding is connected via a scanner switch, a display circuit for displaying the output of this analog-to-digital converter, and a connection between the scanner switch and the analog-to-digital converter via a switch. The measuring device is equipped with a current source that detects a disconnection in the signal source under test by sequentially applying current from the current source to an insulating circuit via a switch. A multi-point data measuring device having a sequence characterized in that the sequence is performed after channel measurement is completed.