addded safety net against misreported values by the temperature controller

1 files changed, 18 insertions, 4 deletions

diff --git a/qolab/hardware/i_server/i800.py b/qolab/hardware/i_server/i800.py
index 318be11..2b3f55f 100644
--- a/qolab/hardware/i_server/i800.py
+++ b/qolab/hardware/i_server/i800.py
@@ -30,15 +30,19 @@ class I800(BasicInstrument):
         self.config['FnamePrefix'] = 'temperature'
         self.deviceProperties = {'Temperature', 'SetPoint1', 'SetPoint2'}
 
-    def query(self, cmnd):
+    def query(self, cmnd, trials=10):
         modbus_cmnd = f'{self.modbus_address}{cmnd}'
         qstr=f'POST / HTTP/1.1\r\n\r\n{self.cmd_start_marker}{modbus_cmnd}\r\n'
         s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         s.connect((self.host, self.port))
         s.send(qstr.encode('ascii'))
         reply = s.recv(100).decode('ascii')
+        s.close()
         if reply[0:5] != f'{modbus_cmnd}':
             # check the proper echo response
+            print(f'Warning: expected {modbus_cmnd} but got {reply[0:5]}')
+            if trials > 0:
+                return self.query(cmnd, trials -1 )
             return None
         return reply[5:-1] # last symbol is '\r'
 
@@ -46,7 +50,11 @@ class I800(BasicInstrument):
     @cached(cache=TTLCache(maxsize=1, ttl=TTL_MEASURED))
     def getTemperature(self):
         command='X01'; # give decimal representation (X) of the temperature (01 address)
-        return float(self.query(command))
+        reply=self.query(command)
+        if reply is not None:
+            return float(reply)
+        else:
+            return float('nan')
 
     def setPoinStr2value(self, spStr):
         raw = int(spStr, 16)
@@ -75,14 +83,20 @@ class I800(BasicInstrument):
     def getSetPoint1(self):
         command='R01'
         reply=self.query(command)
-        return (self.setPoinStr2value(reply))
+        if reply is not None:
+            return (self.setPoinStr2value(reply))
+        else:
+            return float('nan')
 
     @BasicInstrument.tsdb_append
     @cached(cache=TTLCache(maxsize=1, ttl=TTL_SEATABLES))
     def getSetPoint2(self):
         command='R02'
         reply=self.query(command)
-        return (self.setPoinStr2value(reply))
+        if reply is not None:
+            return (self.setPoinStr2value(reply))
+        else:
+            return float('nan')
     
 if __name__ == '__main__': 
     tc = I800()