extra safety net for replies from iServer

1 files changed, 6 insertions, 4 deletions

diff --git a/qolab/hardware/i_server/i800.py b/qolab/hardware/i_server/i800.py
index 2b3f55f..b7b2fc9 100644
--- a/qolab/hardware/i_server/i800.py
+++ b/qolab/hardware/i_server/i800.py
@@ -38,13 +38,15 @@ class I800(BasicInstrument):
         s.send(qstr.encode('ascii'))
         reply = s.recv(100).decode('ascii')
         s.close()
+        rlist=reply.split(); # occasionally there is more than one reply, it also removes \r
+        reply=rlist[-1];     # we will use the last one
         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'
+        return reply[5:]
 
     @BasicInstrument.tsdb_append
     @cached(cache=TTLCache(maxsize=1, ttl=TTL_MEASURED))
@@ -72,11 +74,11 @@ class I800(BasicInstrument):
         elif raw & (0b100 << 20):
             scale = 100
         else:
-            print('Error: unknown decimal point position')
-            return None
+            print(f'Error: unknown decimal point position in decoded {spStr}')
+            return float('nan')
 
         val = raw & 0xFFFFF
-        return(sign*val/scale)
+        return float(sign*val/scale)
 
     @BasicInstrument.tsdb_append
     @cached(cache=TTLCache(maxsize=1, ttl=TTL_SEATABLES))