CN201707396U - Sequence testing circuit - Google Patents

Abstract

A sequence testing circuit, comprising resistors R1, R2, R3, a capacitor C1 and a light electric coupler U1; the tested sequence signal is induced to the input end of the light electric coupler U1 through the current limiting resistor R1 and an RC filter formed by parallel connecting the resistor R2 and the capacitor C1; an output end anode of the light electric coupler U1 is connected with the resistor R3 in series and then connected with a power supply Vcc; and the output end anode of the light electric coupler U1 is directly extracted for sampling the testing signal at the I/O interface of the testing computer, and the output end cathode of the light electric coupler U1 is connected with the ground. Compared with the existing sequence testing method, the sequence testing circuit of the utility model solves the problem that sequence cannot be tested; synchronously, the sequence testing circuit tests the sequence signal after the sequence signal is subjected to photoelectric isolation by using the light electric coupler thereby guaranteeing validity and reliability of the acquired signal at the back end; meanwhile, the input end of the light electric coupler is in parallel connection with the RC filter, so that interference on the sequence testing circuit is reduced effectively, and the reliability thereof is improved.

Description

A kind of timing sequence test circuit

Technical field

The utility model relates to a kind of optocoupler test circuit, relates in particular to a kind of timing sequence test circuit, is mainly used in the sequential output self-test of sequential output device.

Background technology

At present, the sequential output test of aircraft is all finished on ground, generally directly draw the simulating signal of sequential output to the ground launch vehicle measurement from aircraft with point-to-point mode, ground is tested with pilot lamp or other test circuit again, this method of testing can only competence exertion effect when ground experiment, for the output of the sequential in the real flight course of aircraft, traditional method of testing will lose efficacy.

The utility model content

Technology of the present utility model is dealt with problems and is: overcome the deficiencies in the prior art, a kind of timing sequence test circuit is provided, by adopting the test of a highly reliable optocoupler test circuit realization to clock signal, this circuit is simple and reliable, volume is little, cost is low, the reliability height.

Technical solution of the present utility model is: a kind of timing sequence test circuit, it is characterized in that: comprise test input interface circuit and optocoupler test output circuit, described test input interface circuit comprises current-limiting resistance R1, resistance R 2 and capacitor C 1, resistance R 2 and capacitor C 1 compose in parallel the RC wave filter, form the test input interface circuit after the RC wave filter is connected with current-limiting resistance R1; Described optocoupler test output circuit comprises photoelectrical coupler U1 and resistance R 3, two input ends of photoelectrical coupler U1 link to each other with the two ends of RC wave filter respectively, the output plus terminal of photoelectrical coupler U1 with connect power Vcc after resistance R 3 is connected, the output negativing ending grounding of photoelectrical coupler U1, the output plus terminal of photoelectrical coupler U1 are drawn and are exported test computer to as test signal and sample.

Its principle of work is: tested clock signal is through current-limiting resistance R1, cause the input end of photoelectrical coupler U1 again through the RC wave filter of resistance R 2 and capacitor C 1 formation in parallel, when the test circuit input end does not have sequential output, not conducting of photoelectrical coupler U1, the timing sequence test signal that test computer I/O mouth receives is a high level, when the test circuit input end has sequential output, photoelectrical coupler U1 conducting, the timing sequence test signal that test computer I/O mouth receives is a low level.

The utility model beneficial effect compared with prior art is: the utility model is by realizing the self-test function of sequential output device at the built-in highly reliable optocoupler test circuit of sequential output device, because circuit directly is integrated in the vehicle-borne equipment, even under the aircraft flight state, test circuit still can collect the output state of sequential, compare existing timing sequence test method, solved the problem that sequential can't be tested in the aircraft flight process, adopt photoelectrical coupler that clock signal is carried out testing after photoelectricity is isolated again simultaneously, the validity and the reliability of the test signal that the rear end collects have been guaranteed, simultaneously, the input end of optocoupler RC wave filter in parallel, effectively reduce the interference on the timing sequence test circuit, improved the reliability of timing sequence test circuit.

Description of drawings

Fig. 1 is a circuit theory synoptic diagram of the present utility model.

Embodiment

Be that 28V is that example provides specific implementation method of the present utility model with the sequential output voltage below.

As shown in Figure 1, U1 is the main devices that realizes test circuit as photoelectrical coupler, conducting after the test circuit input end is introduced clock signal, and the circuit output end output low level is given the test of the current preface of test computer I/O cause for gossip.Be connected in parallel resistance R 2 and capacitor C 1 of device input end behind the photoelectricity coupling, one of them input endpoint is connected by the sequential output terminal of sequential output device on series limiting resistor R1 and the bullet, and another input end of device U1 is connected to the negative terminal of clock signal correspondence behind the photoelectricity coupling.The output of photoelectrical coupler U1 card end is connected with power Vcc by resistance in series R3, exports negative terminal and is connected to power Vcc accordingly, and output plus terminal is drawn and exported test computer to as test signal and sample.According to the running parameter of photoelectrical coupler, can be by suitably selecting resistance and the capacitor C1 appearance value of resistance R 1, R2, R3, the actual reliably working parameter of design optocoupler U1.

The course of work of described technical scheme is:

(1) relay K 1 disconnects, the sequential no-output, and photoelectrical coupler U1 is not because the input two ends form power circuit and not conducting, and this moment, photoelectrical coupler U1 output plus terminal was high level state, and test computer I/O mouth receives high level;

(2) relay K 1 closure, sequential output, photoelectrical coupler U1 conducting, photoelectrical coupler U1 output plus terminal is low level state by negative terminal and ground short circuit at this moment, and test computer I/O mouth receives low level.

At the technical scheme shown in the embodiment, when concrete the application, relate generally to the selection of optocoupler and the selection of capacitance-resistance parameter.Among Fig. 1, the GH281-4 type photoelectrical coupler that photoelectrical coupler U1 can select for use the Rui Pubei photoproduction to produce, photoelectrical coupler conducting electric current is 1-20mA, forward voltage V _FBe 1.0-1.5V, output conduction voltage drop V after the photoelectrical coupler conducting _OBe 0.1～0.3V, the transfer ratio CTR of photoelectrical coupler electric current is 300%.Resistance R 2 and capacitor C 1 are mainly used in filtering and improve the input signal thresholding, and the C1 appearance is worth optional 0.047 μ F, and the R2 resistance is got 200 Ω; Resistance R 1 constitutes dividing potential drop, divided circuit with R2, and the R1 resistance is got 1800 Ω.The test circuit running parameter specifically is calculated as follows:

The threshold voltage of test circuit:

$(\frac{\mathrm{VCC}-V_O}{R3\×\mathrm{CTR}}+\frac{V_F}{R2})\×R1+V_F=(\frac{5-0.2}{1000\×3}+\frac{1.2}{200})\×1800+1.2\≈14.8V$

Test circuit conducting minimum current:

$\frac{\mathrm{VCC}-V_O}{R3\×\mathrm{CTR}}=\frac{5-0.2}{1000\×3}\≈1.6\mathrm{mA}$

The test circuit working current is:

$\frac{+D-V_F}{R1}-\frac{V_F}{R2}=\frac{28-1.2}{1800}-\frac{1.2}{200}\≈8.9\mathrm{mA}$

Aforementioned calculation result shows that the technical scheme of present embodiment can normally detect the sequential output signal.

The utility model not detailed description is a technology as well known to those skilled in the art.

Claims (3)

1. timing sequence test circuit, it is characterized in that: comprise test input interface circuit and optocoupler test output circuit, described test input interface circuit comprises current-limiting resistance R1, resistance R 2 and capacitor C 1, resistance R 2 and capacitor C 1 compose in parallel the RC wave filter, form the test input interface circuit after the RC wave filter is connected with current-limiting resistance R1; Described optocoupler test output circuit comprises photoelectrical coupler U1 and resistance R 3, two input ends of photoelectrical coupler U1 link to each other with the two ends of RC wave filter respectively, the output plus terminal of photoelectrical coupler U1 with connect power Vcc after resistance R 3 is connected, the output negativing ending grounding of photoelectrical coupler U1, the output plus terminal of photoelectrical coupler U1 are drawn and are exported test computer to as test signal and sample.

2. a kind of timing sequence test circuit according to claim 1, it is characterized in that: described photoelectrical coupler U1 selects GH281-4 type photoelectrical coupler for use, the conducting electric current of photoelectrical coupler U1 is 1-20mA, forward voltage is 1.0-1.5V, and the output conduction voltage drop is 0.1～0.3V after the photoelectrical coupler U1 conducting.

3. a kind of timing sequence test circuit according to claim 1 is characterized in that: the resistance of described resistance R 2 is 200 Ω, and the appearance value of capacitor C 1 is 0.047 μ F, and the resistance of current-limiting resistance R1 is 1800 Ω.