Software/Python

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Currently we have limited experience with Python, but here are a few simple programs to get you started communicating with Zaber devices. Note that in order to use the serial port in python you must install the pyserial module. See http://pyserial.sourceforge.net/ for more information.

Contents

Displaying a list of available serial ports

The following program will work in Windows or Linux. It should display all resident serial ports, but in Linux it may miss virtual ports (ex USB to serial converters).

#! /usr/bin/env python

import serial

def scan():
   # scan for available ports. return a list of tuples (num, name)
   available = []
   for i in range(256):
       try:
           s = serial.Serial(i)
           available.append( (i, s.portstr))
           s.close()
       except serial.SerialException:
           pass
   return available

print "Found ports:"
for n,s in scan(): print "(%d) %s" % (n,s)

The following program will work only in Linux. It will display all serial ports including virtual ports (ex USB to serial converters).

#! /usr/bin/env python
import serial, glob

def scan():
   # scan for available ports. return a list of device names.
   return glob.glob('/dev/ttyS*') + glob.glob('/dev/ttyUSB*')

print "Found ports:"
for name in scan(): print name

Opening a serial port, sending an instruction, and receiving a reply

The following code opens the serial port "/dev/ttyUSB0" (a USB to serial adapter installed on a Linux machine) and sends an instruction to a Zaber device to return its power supply voltage. After 1 second, the program checks for a response and displays it.

#!/usr/bin/env python
import serial, sys, time, glob, struct

def send(device, command, data=0):
   # send a packet using the specified device number, command number, and data
   # The data argument is optional and defaults to zero
   packet = struct.pack('<BBl', device, command, data)
   ser.write(packet)

def receive():
   # return 6 bytes from the receive buffer
   # there must be 6 bytes to receive (no error checking)
   r = [0,0,0,0,0,0]
   for i in range (6):
       r[i] = ord(ser.read(1))
   return r

# open serial port
# replace "/dev/ttyUSB0" with "COM1", "COM2", etc in Windows
try:
   ser = serial.Serial("/dev/ttyUSB0", 9600, 8, 'N', 1, timeout=5)   
except:
   print("Error opening com port. Quitting.")
   sys.exit(0)
print("Opening " + ser.portstr)

device = 1
command = 52
data = 0
print('Sending instruction. Device: %i, Command: %i, Data: %i' % (device, command, data))
send(device, command, data)
time.sleep(1) # wait for 1 second

try:
   reply = receive()
   # Reply data is calculated from all reply bytes
   replyData = (256.0**3.0*reply[5]) + (256.0**2.0*reply[4]) + (256.0*reply[3]) + (reply[2])
   if reply[5] > 127:
      replyData -= 256.0**4
   
   print("Receiving reply " + str(reply))
   print("Device number: " + str(reply[0]))
   print("Command number: " +  str(reply[1]))
   print("Supply voltage: " + str(replyData/10) + "V") # Supply voltage must be divided by ten
except:
   print("No reply was received.")
   
print("Closing " + ser.portstr)
ser.close() 

Open-Source Zaber Python Library

One of our customers kindly created an open-source Zaber library for Python.

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