frappy_psi.ahcapbridge: fix behaviour when serial echo is on

frappy_psi/ahcapbridge.py

@@ -51,13 +51,31 @@ class IO(StringIO):
     end_of_line = ('\r\n', '\r')
     timeout = 5
     sent_command = False  # used to detect that communicate was called directly
+    ECHO = re.compile('>|AV |VO |FR |SI |SH ')  # this is recognized as an echo
+    MEAS = re.compile(' *([FC]=|NO DATA)')  # overriden by the module 
 
     @Command(StringType(), result=StringType())
     def communicate(self, command, noreply=False):
         """communicate and remind that a command was sent"""
         # this is also called by writeline
         self.sent_command = True
-        return super().communicate(command, noreply)
+        for _ in range(3):
+            reply = super().communicate(command, noreply)
+            reply = reply and reply.strip()
+            if self.check_echo_off(reply):
+                 return reply
+        raise CommunicationFailedError('detected echo but can not switch off')
+
+    def check_echo_off(self, reply):
+        if self.ECHO.match(reply or ''):
+            super().writeline('\rSERIAL ECHO OFF;UN 2')
+            for _ in range(3):
+                reply = self.readline()
+                if self.MEAS.match(reply or ''):
+                    # this is a meas reply
+                    break
+            return False
+        return True
 
 
 class AHBase(HasIO, Pinata, Acquisition):
@@ -86,17 +104,19 @@ class AHBase(HasIO, Pinata, Acquisition):
 
     export = True  # for a Pinata module, the default is False!
     ioClass = IO
-    COMMANDS = ['AV', 'VO', 'SI', 'SH', 'FR']
     _error = ''
     _last_start = None
     _params = None
     _mode = CONTINUOUS  # or RUNNING or FINISHED
     _cont_deadline = 0  # when to switch back to continuous after finished
     _averexp_deadline = 0  # to make sure averexp is polled periodically
+    _lossunit = 'undefined'
     # to be overridden:
     PATTERN = None  # a list of patterns to parse replies
     MEAS_PAT = None  # the pattern to parse the measurement reply
     UNIT = None  # our desired loss unit
+    MODEL_PAT = None
+    MODEL = None
 
     def scanModules(self):
         if self.loss_module:
@@ -108,14 +128,17 @@ class AHBase(HasIO, Pinata, Acquisition):
                 'cap': self.name}
 
     def initModule(self):
-        self.io.setProperty('identification',
-                            [('\rSERIAL ECHO OFF;SH MODEL',
-                              'ILLEGAL WORD: MODEL')])
         super().initModule()
-        self.echo = re.compile('|'.join(self.COMMANDS))
-        self._params = {}
         self._lock = threading.RLock()
+        self.io.MEAS = self.MEAS_PAT
+        self.io.checkHWIdent = self.checkHWIdent
 
+    def checkHWIdent(self):
+        for _ in range(3):
+            if self.MODEL_PAT.match(self.communicate('SH MODEL')):
+                return
+        raise CommunicationFailedError(f'we are not connected to a {self.MODEL}')
+ 
     def initialReads(self):
         # UN 2 does also return the results of the last measurement
         # (including the frequency for AH2700)
@@ -125,8 +148,8 @@ class AHBase(HasIO, Pinata, Acquisition):
         self.goal = self.averexp
         self.single_meas()
 
-    def communciate(self, command):
-        reply = self.io.communciate(command)
+    def communicate(self, command):
+        reply = self.io.communicate(command)
         self.io.sent_command = False
         return reply
 
@@ -176,7 +199,6 @@ class AHBase(HasIO, Pinata, Acquisition):
         match = self.MEAS_PAT.match(reply)
         if match:
             return match.groupdict()
-        self.log.warn('got unexpected message %r from SI', reply)
         return {}
 
     def doPoll(self):
@@ -188,7 +210,7 @@ class AHBase(HasIO, Pinata, Acquisition):
             if meas:
                 self.update_meas(**meas)
             else:
-                self.log.warn('unexpected reply: %r', reply)
+                self.io.check_echo_off(reply)
                 self.retrigger_meas()
         elif self._mode == FINISHED and time.time() > self._cont_deadline:
             self._mode = CONTINUOUS
@@ -331,18 +353,14 @@ class AH2550(AHBase):
         r'V= *(?P<voltage>[0-9.E+-]+) *V,A,*(?P<error>.*)$'
     )
     UNIT = 'DF'
+    MODEL_PAT = re.compile('ILLEGAL WORD: MODEL')
+    MODEL = 'AH2550'
 
     # empirically determined - may vary with noise
     # differs drastically from the table in the manual
     MEAS_TIME_CONST = [0.2, 0.3, 0.4, 1.0, 1.3, 1.6, 2.2, 3.3,
                        5.5, 8.3, 14, 25, 47, 91, 180, 360]
 
-    def initModule(self):
-        self.io.setProperty('identification',
-                            [('\rSERIAL ECHO OFF;SH MODEL',
-                              'ILLEGAL WORD: MODEL')])
-        super().initModule()
-
     def _calculate_time(self, averexp, freq):
         self.calculated_time = self.calculate_time(averexp)
 
@@ -372,12 +390,8 @@ class AH2700(AHBase):
         f'V= *(?P<voltage>[0-9.E+-]+) *V *(?P<error>.*)$'
     )
     UNIT = 'DS'
-
-    def initModule(self):
-        super().initModule()
-        self.io.setProperty('identification',
-                            [('\r\nSERIAL ECHO OFF;SH MODEL',
-                              'MODEL/OPTIONS *AH2700')])
+    MODEL_PAT = re.compile('MODEL/OPTIONS *AH2700')
+    MODEL = 'AH2700'
 
     def scanModules(self):
         yield from super().scanModules()