watchdog.py 文件源码

def expir_trig_dig_edge_src(self):
        """
        str: Specifies the name of a terminal where a digital signal
            exists to use as the source of the Expiration Trigger.
        """
        cfunc = lib_importer.windll.DAQmxGetDigEdgeWatchdogExpirTrigSrc
        if cfunc.argtypes is None:
            with cfunc.arglock:
                if cfunc.argtypes is None:
                    cfunc.argtypes = [
                        lib_importer.task_handle, ctypes.c_char_p,
                        ctypes.c_uint]

        temp_size = 0
        while True:
            val = ctypes.create_string_buffer(temp_size)

            size_or_code = cfunc(
                self._handle, val, temp_size)

            if is_string_buffer_too_small(size_or_code):
                # Buffer size must have changed between calls; check again.
                temp_size = 0
            elif size_or_code > 0 and temp_size == 0:
                # Buffer size obtained, use to retrieve data.
                temp_size = size_or_code
            else:
                break

        check_for_error(size_or_code)

        return val.value.decode('ascii')