Seeking clipping detection example for MSO46B

[driftregion]

Hello,

I am using an MSO46B with tm_devices==3.3.0 in an automated testbench.
What I am trying to do is:

1. set the scope acquisition state to RUN
2. command another instrument which results in a clean rising edge TTL signal upon which the scope triggers
3. wait for the acquisition to complete
4. check for clipping on any of the sampled signals. If there is clipping, rescale and return to step 1
5. grab the waveform data via HSI

I am reading 4-5-6_MSO_ProgrammerManual-077189800.pdf as well as the source, examples and tests of tm_devices but I am unable to figure out how to make this work reliably. This is challenging because I am working between three different partially-overlapping APIs: the SCPI interface, the tm_devices interface, and the tek_hsi interface.

I am experiencing an issue on step 4. Using the CHx:CLIPPING? query returns 0 even when the waveform data is obviously saturated. I am able to get a more reliable result by configuring a measurement on CHx, (e.g. Peak-to-Peak) and monitoring ESR and EVMSG for measurement warnings and errors related to clipping. However, this too is cumbersome as I have not found a way to associate those errors with a specific channel.

Is it possible to provide a simple example of how to detect and rescale to achieve maximum usage of the vertical scale?

    def get_data(self, burst_num_cycles: int):
        n = 0

        self.scope.inst.commands.acquire.stopafter.write("SEQuence")

        while True:
            self.scope.inst.commands.acquire.state.write("RUN")
            self.scope.inst.poll_query(
                number_of_polls=100,
                query="TRIGger:STATE?",
                wanted_val="READY",
                sleep_time=0.001,
            )

            self.fun.inst.write(f"INV:BURSTCYCles {int(burst_num_cycles)}")

            self.scope.inst.commands.opc.query()

            self.scope.inst.poll_query(
                number_of_polls=100,
                query="TRIGger:STATE?",
                wanted_val="SAVE",
                sleep_time=0.001,
            )

            with self.scope.hsi.access_data(AcqWaitOn.AnyAcq):

                needs_rescale = False

                ch2_scale = float(self.scope.inst.query("CH2:SCAle?"))
                vpkpk2 = float(self.scope.inst.query("MEASUrement:MEAS1:VALue?"))

                esr = int(self.scope.inst.commands.esr.query())
                if esr:
                    evmsg = self.scope.inst.commands.evmsg.query()
                    import ipdb; ipdb.set_trace()


                print(f"vpkpk2: {vpkpk2}")
                print(f"clipping?: {self.scope.inst.commands.ch[2].clipping.query()}")
                print(f"clipping?: {self.scope.inst.query('CH2:CLIPping?')}")
                if int(self.scope.inst.query("CH2:CLIPping?")) == 1:
                    print("CH2 is clipping")
                    self.scope.inst.write(f"CH2:SCAle {ch2_scale * 2}")
                    needs_rescale = True
                if vpkpk2 < ch2_scale:
                    self.scope.inst.write(f"CH2:SCAle {ch2_scale / 2}")
                    needs_rescale = True

                ipkpk = float(self.scope.inst.query("MEASUrement:MEAS3:VALue?"))
                print(f"ipkpk: {ipkpk}")
                print(f"clipping?: {self.scope.inst.commands.ch[4].clipping.query()}")
                print(f"clipping?: {self.scope.inst.query('CH4:CLIPping?')}")
                ch4_scale = float(self.scope.inst.query("CH4:SCAle?"))

                if int(self.scope.inst.query("CH4:CLIPping?")) == 1:
                    print("CH4 is clipping")
                    self.scope.inst.write(f"CH4:SCAle {ch4_scale * 2}")
                    needs_rescale = True
                if ipkpk < ch4_scale:
                    self.scope.inst.write(f"CH4:SCAle {ch4_scale / 2}")
                    needs_rescale = True

                if needs_rescale:
                    n += 1
                    print(f"Scope rescaled {n} times, acquiring once more...")
                    self.scope.inst.write("ACQuire:STATE STOP")
                    self.scope.inst.query("*OPC?")                # fence after scale changes
                    continue

                ch1 = self.scope.hsi.get_data("ch1")
                ch2 = self.scope.hsi.get_data("ch2")
                ch3 = self.scope.hsi.get_data("ch3")
                ch4 = self.scope.hsi.get_data("ch4")

                assert (
                    len(ch1.normalized_vertical_values)
                    == len(ch2.normalized_vertical_values)
                    == len(ch3.normalized_vertical_values)
                    == len(ch4.normalized_vertical_values)
                ), "Channel data lengths do not match"
                return {
                    "vin": ch1.normalized_vertical_values,
                    "vcap": ch2.normalized_vertical_values,
                    "icvr": ch4.normalized_vertical_values,
                    "time_vec": ch1.normalized_horizontal_values,
                }

Kind regards,
Nick

[driftregion]

Here is an example of the behavior I am observing: CH2 is clearly clipping but CH2:CLIPPING? returns 0:

[driftregion]

I have found that it is possible to query whether or not a particular measurement has warnings or errors with the following procedure:

1. query *ESR? to clear the ESR register
2. query the desired measurement, e.g. MEASUrement:MEAS3:VALue?
3. again query *ESR? to check whether or not there is an error associated with query 2.
4. if there is, query EVENT? to get the exact error code.
5. repeat for all desired measurements.