fix new statemachine with ips magfield

+ add on_error, on_restart etc. to states.py
+ add n_retry argument to mercury change/multichange

secop_psi/mercury.py

@@ -123,13 +123,14 @@ class MercuryChannel(HasIO):
         else:
             raise HardwareError(msg) from None
 
-    def multichange(self, adr, values, convert=as_float, tolerance=0):
+    def multichange(self, adr, values, convert=as_float, tolerance=0, n_retry=3):
         """set parameter(s) in mercury syntax
 
         :param adr: as in see multiquery method
         :param values: [(name1, value1), (name2, value2) ...]
         :param convert: a converter function (converts given value to string and replied string to value)
         :param tolerance: tolerance for readback check
+        :param n_retry: number of retries or 0 for no readback check
         :return:  the values as tuple
 
         Example:
@@ -143,7 +144,7 @@ class MercuryChannel(HasIO):
         adr = self._complete_adr(adr)
         params = ['%s:%s' % (k, convert(v)) for k, v in values]
         cmd = 'SET:%s:%s' % (adr, ':'.join(params))
-        for _ in range(3):  # try 3 times or until readback result matches
+        for _ in range(max(1, n_retry)):  # try n_retry times or until readback result matches
             t = time.time()
             reply = self.communicate(cmd)
             head = 'STAT:SET:%s:' % adr
@@ -158,6 +159,8 @@ class MercuryChannel(HasIO):
             except (AssertionError, AttributeError, ValueError) as e:
                 time.sleep(0.1)  # in case of missed replies this might help to skip garbage
                 raise HardwareError('invalid reply %r to cmd %r' % (reply, cmd)) from e
+            if n_retry == 0:
+                return [v[1] for v in values]  # no readback check
             keys = [v[0] for v in values]
             debug = []
             readback = self.multiquery(adr, keys, convert, debug)
@@ -182,9 +185,9 @@ class MercuryChannel(HasIO):
         adr, _, name = adr.rpartition(':')
         return self.multiquery(adr, [name], convert)[0]
 
-    def change(self, adr, value, convert=as_float, tolerance=0):
+    def change(self, adr, value, convert=as_float, tolerance=0, n_retry=3):
         adr, _, name = adr.rpartition(':')
-        return self.multichange(adr, [(name, value)], convert, tolerance)[0]
+        return self.multichange(adr, [(name, value)], convert, tolerance, n_retry)[0]
 
 
 class TemperatureSensor(MercuryChannel, Readable):