rewrite read and write communication with bk_5491

1 files changed, 64 insertions, 45 deletions

diff --git a/qolab/hardware/multimeter/bk_5491.py b/qolab/hardware/multimeter/bk_5491.py
index 0b9d788..cca8d7f 100644
--- a/qolab/hardware/multimeter/bk_5491.py
+++ b/qolab/hardware/multimeter/bk_5491.py
@@ -22,9 +22,12 @@ class BK_5491(Multimeter):
         self.resource.stop_bits = pyvisa_constants.StopBits.one
         self.resource.timeout = 5000
 
-        self.write = self.resource.write
         self.read = self.resource.read
-        self.query = self.resource.query
+        # we need to work around the prompts which BK_5491 sends during
+        # communication to mimic SCPI
+        # if you need raw connection use self.resource.write or self.resource.query
+        # self.write = self.resource.write
+        # self.query = self.resource.query
         self.read_bytes = self.resource.read_bytes
         self.read_binary_values = self.resource.read_binary_values
         self.query_binary_values = self.resource.query_binary_values
@@ -43,88 +46,104 @@ class BK_5491(Multimeter):
         print(f'Error detected {prompt=}')
         return False
 
-    def sendCmd(self, cmd_string, expect_reply=True, Nattemts=5):
+    def write(self, cmd_string):
+        return self._readwrite(cmd_string, expect_reply=False, Nattemts=1)
+    def query(self, cmd_string):
+        return self._readwrite(cmd_string, expect_reply=True, Nattemts=5)
+
+    def _readwrite(self, cmd_string, expect_reply=True, Nattemts=5):
         """
         Set command to instrument or query it readings (which is also a command)
 
-        BK_5491 in not SCPI instrument, so we get some replies (prompts *>, =>, etc)
+        BK_5491 is not a SCPI instrument, so we get some replies (prompts *>, =>, etc)
         even if we just send a command not a query. So we have to work around this.
         """
         self.resource.read_bytes( self.resource.bytes_in_buffer ) # clear read buffer
         # print(f"dbg: {cmd_string=}")
-        self.write(cmd_string)
+        self.resource.write(cmd_string)
         if expect_reply:
-            reply = self.read() # this should be result
+            reply = self.resource.read() # this should be result
             # print(f"dbg: {reply=}")
             if self.isPrompt(reply):
-                # print(f'Error: we ask {cmd_string=} and got prompt "{reply}" instead of result')
                 prompt = reply
                 if prompt[0] == '@':
                     if Nattemts >= 2:
                         # print('dbg: numeric reading is not available yet, attempt one more time')
                         time.sleep(self.switchTime)
-                        return self.sendCmd(cmd_string, expect_reply=expect_reply, Nattemts=Nattemts-1)
+                        return self._readwrite(cmd_string, expect_reply=expect_reply, Nattemts=Nattemts-1)
+                print(f'Error: we ask {cmd_string=} and got prompt "{reply}" instead of result')
                 return None
         else:
             reply = None
-        prompt = self.read() # this should be prompt
-        self.isPromptGood(prompt)
-        # print(f"dbg: {prompt=}")
+        prompt = self.resource.read() # this should be prompt
+        if not self.isPromptGood(prompt):
+            print(f'Error: expected good prompt but got "{prompt=}"')
         return reply
 
     def getReading(self):
-       """ Report current measurement """
-       ret_string = self.sendCmd('R1')
+       """ Report current measurement displayed on the first/main display """
+       ret_string = self.query('R1')
        # print(f'dbg: getReading received "{ret_string}"')
        return float(ret_string)
 
-    def setFunction(self, key_string):
-        """
-        BK_5491 set the measurement functions according to the front panel keys:
-            K1 - Vdc
-            K2 - Adc
-            K3 - Vac
-            K4 - Aac
-            K5 - Resistance
-            K6 - Diode
-            K7 - Frequency (Hz)
-            K8 - Auto
-            K9 - Up key
-            K10 - Down key
-            K11 - MinMax key
-            K12 - Hold key
-            K13 - Local (manual does not specify, but it works this way)
-            K14 - Rel key
-            K15 - Shift key
-            K16 - 2nd key
-            K17 - Vdc and Vac keys simultaneously
-            K18 - Adc and Aac keys simultaneously
-            K19 - Shift then Up keys (increasing the intensity of the VFD display)
-            K20 - Shift then Down keys (decreasing the intensity of the VFD display)
-        """
-
+    """
+    BK_5491 has two displays which could be set and read separately,
+    here we use only setting of the 1st display (prefix S1 below)
+    to set the measurement and read it later.
+    It is also possible to set range, but I prefer to leave in to
+    the front panel user.
+    If this is needed it would be followed by 3 symbols specifiers as
+    outline in the manual.
+    """
     def getVdc(self):
-        self.sendCmd('K1')
+        self.write('S10')
         return self.getReading()
     def getVac(self):
-        self.sendCmd('K3')
+        self.write('S11')
         return self.getReading()
     def getAdc(self):
-        self.sendCmd('K2')
+        self.write('S14')
         return self.getReading()
     def getAac(self):
-        self.sendCmd('K4')
+        self.write('S15')
         return self.getReading()
     def getResistance(self):
-        self.sendCmd('K5')
+        self.write('S12')
+        return self.getReading()
+    def getResistance4Wires(self):
+        self.write('S13')
         return self.getReading()
     def getDiode(self):
-        self.sendCmd('K6')
+        self.write('S16')
         return self.getReading()
     def getFreq(self):
-        self.sendCmd('K7')
+        self.write('S17')
         return self.getReading()
 
+    """
+    With BK_5491
+    It is possible to send "key presses" like they are coming from the front panel
+        K1 - Vdc
+        K2 - Adc
+        K3 - Vac
+        K4 - Aac
+        K5 - Resistance
+        K6 - Diode
+        K7 - Frequency (Hz)
+        K8 - Auto
+        K9 - Up key
+        K10 - Down key
+        K11 - MinMax key
+        K12 - Hold key
+        K13 - Local (manual does not specify, but it works this way)
+        K14 - Rel key
+        K15 - Shift key
+        K16 - 2nd key
+        K17 - Vdc and Vac keys simultaneously
+        K18 - Adc and Aac keys simultaneously
+        K19 - Shift then Up keys (increasing the intensity of the VFD display)
+        K20 - Shift then Down keys (decreasing the intensity of the VFD display)
+    """
     def toLocal(self):
         self.sendCmd('K13', expect_reply=False)