Create picomotor_driver.py

Picomotor/picomotor_driver.py

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+"""
+Library to control the NewFocus 8732 picomotor driver.
+"""
+import serial
+import time
+import numpy as np
+
+
+class picomotor:
+    axis_names = { "MOTz_x": "112", "MOTz_y": "122"} 
+    steps_in_turn = { "MOTz_x": [1000,1000], "MOTz_y": [1000,1000]} # [CW, CCW] number of steps for 1 turn
+
+
+    def __init__(self, COM_port )
+        """Open serial connection for NewFocus 8732 controller"""
+        """COM_port:  ie 'COM3' (check device manager) """
+
+        self.serial = serial.Serial(timeout = 0.5) #19200 baud didn't work. 8 bits, no parity, 1 stop bit.
+        self.serial.baudrate = 9600
+        self.serial.port = COM_port #'COM3'
+        #print("Serial connection open: ", self.serial.open())
+        response = self.sendreceive(self, "*IDN?")
+        print(response)
+
+
+        # Initialize positions
+        self.positions =  dict.fromkeys(axis_names, 0) #{'MOTz_x': 0, 'MOTz_y': 0, ...} #units steps
+
+        # Turn on the slots?
+        #self.sendreceive(':INST 1') #? not sure if I need this?
+        #INST:NSEL 1
+
+
+    def sendreceive(self, cmd):
+        """Send command to the picomotor driver, and readlines"""
+        """ Send multiple commands with ;"""
+        """ 8732 ends with carriage return \r. Does not echo command, but always responds. """
+        line = cmd + '\r'
+        retval = self.serial.write(bytes(line, encoding='ascii'))
+        time.sleep(0.01) #not sure if need
+        response = self.serial.read_until(b'\r')
+        #self.serial.flush() #what does this do?
+        return response
+
+
+    def move_abs(self, axis, position, velocity)
+        """ Move to absolute position, and if CCW (negative steps), then use correct cw/ccw disparities"""
+        cw ccw = steps_in_turn[axis] #number steps in turn
+        current_position = self.positions[axis] #get current position
+        steps = position - current_position
+
+        if steps < 0:
+            steps = steps*(ccw/cw)
+
+        self.move(axis, steps, velocity)
+        self.positions[axis] = position
+
+
+    def move(self, axis, steps, velocity)
+        """ Move relative number of setups.  Position CW, Negative CCW"""
+        """ Returns before finished moving. """
+
+        cmd1 = "INST:NSEL " + axis_names[axis]
+
+        if steps < 0:
+            cmd2 = ":SOUR:DIR CWW"
+        else:
+            cmd2 = ":SOUR:DIR CW"
+
+        cmd3 = "SOUR:PULS:FREQ "+ str(round(velocity)) # integer divider of 1500
+
+        cmd4 = ":SOUR:PULS:COUN " + str(round(abs(steps)))
+
+        cmd = cmd1 + "; " + cmd2 + "; " + cmd3 + "; " + cmd4
+        self.sendreceive(cmd)
+
+        # Update position
+        self.positions[axis] = self.positions[axis] + steps
+
+
+    def wait_for_move(self)
+        """ Wait for picomotor to finish moving """ 
+        timeout = 120 # timeout seconds
+        moving = 1
+        while moving: #OPC returns 1 if all channels are finished
+            time.sleep(0.2)
+            text = self.sendreceive("*OPC?")
+            moving = int(text)# get 1 or 0 from text
+
+
+    def zero_positions(self)
+        """ Zero all positions """ 
+        self.positions =  dict.fromkeys(axis_names, 0) 
+
+    def zero_position(self, axis)
+        """ Zero single axis """ 
+        self.positions[axis] = 0
+