DCITrg [A]

Description of Function

Indirect measurement of current by means of internally or externally triggered integrating DC voltage measurement. Currents flowing into the control unit register as positive. Depending on mode, this function acts as a control function or a measurement function. If it is used as a control function, the test result can be established with the aid of the function RDCITrg IDH_RDCITrg .

Testing Points

The control unit pin is specified as the test point and the reference point.

Parameters

Shuntresistor

For selection of the impedance level:
a) If a component of a simulated load, see MSL Catalogue, Implementation of Modules (Simulated Loads)
b) If exclusively a current measurement resistor, see MSL Catalogue, Current Measurement Using Series Resistor. The maximum permissible testing impedance is specified as the parameter.

MaxSignalAmplitude

Largest amplitude occurring on the signal. Can be used to establish the measurement range or to select a suppressor circuit.

TriggerEdge

Specification of which signal edge is to act as trigger (p = positive edge, n = negative edge).

TriggerLevel

Trigger level for the measurement relative to the trigger signal reference (see example Beispiel_DCITrg ).

TriggerDelay

Trigger delay for measurement (see example Beispiel_DCITrg ).

IntegrationPeriod

Period over which the signal is integrated.
In the event of superimposed interference signals, it is advisable - wherever possible - to select a multiple of the interference signal period as the integration period.
If the integration period determined is less than the testing instrument's shortest integration period, the testing system may use a sample & hold measurement instead of an integrating measurement.

TriggerHigh

Specification of trigger signal:
In the case of external triggering, the control unit pin (e.g. 73) or a (user-) defined signal name from the Signals Table (e.g. UB) is entered here.
In the case of internal triggering (trigger signal = test signal), ´i´ is entered here.

TriggerLow

Specification of trigger signal reference:
In the case of external triggering, the control unit pin (e.g. 68) or a (user-) defined signal name from the Signals Table (e.g. UB) is entered here.
In the case of internal triggering (trigger signal = test signal reference), ´i´ is entered here.

Timeout

If the test read function receives no measured reading input within the period specified for the timeout, the measurement is aborted.
Standard value: 1s

Mode

The Mode indicates whether the function returns a result (m) or whether the testing instrument is simply prepared for the test (s).
Mode m can only be used with periodic test signals. In the case of non-periodic test signals, the test signal is applied and the testing instrument prepared (modes). The trigger event is subsequently activated and then the test read function RDCITrg IDH_RDCITrg invoked.

Example

DCITrg

1,7,p,2.5,10E-6,10E-6,i,i,1,m

Test circuit:

Diagram:

tID,p	Integration period after triggering by positive edge
tID,n	Integration period after triggering by negative edge
tD,p	Delay period after triggering by positive edge
tD,n	Delay period after triggering by negative edge
UTr,p	Trigger level, positive edge
UTr,n	Trigger level, negative edge
Ulow	Low potential of test signal
Uhigh	High potential of test signal

Figure 4: Ignition output stage with regulated current

Trigger level: UTr,p = 0.5(Uhigh - Ulow) + Ulow
UTr,n = 0.5(Uhigh - Ulow) + Ulow

Trigger delay: tD,p = 0.4(t3 - t2) + (t2 - t1)
tD,n = 0.4(t6 - t5) + (t5 - t4)

Integration period: tID,p = 0.2(t3 - t2)
tID,n = 0.2(t6 - t5)