# HG changeset patch
# User Daniel O'Connor <darius@dons.net.au>
# Date 1242200821 -34200
# Node ID 51d1fc44a7533525b55542f6239d76c030d57462
# Parent  6b360c30eed648c71d485dda12b72ef0f89d3984
Add variable timeout for reads.

Modify the example to use it & print how long curve takes.

diff -r 6b360c30eed6 -r 51d1fc44a753 example.py
--- a/example.py	Wed May 13 17:09:14 2009 +0930
+++ b/example.py	Wed May 13 17:17:01 2009 +0930
@@ -10,17 +10,17 @@
     print "Found device"
 
     u.write("*IDN?")
-    print "ID is..",
-    print u.read()
+    print "IDN reports " + u.read()
     
     u.write("DATA:ENC RIB")	# Big endian signed
     u.write("DATA:WIDTH 2")	# 2 bytes wide
     u.write("SELECT:CH1 ON")	# Turn channel 1 on
     u.write("DATA:SOURCE CH1")	# Set the curve source to channel 1
     u.write("CURVE?")		# Ask for the curve data
-    time.sleep(1)		# Wait for the data..
-    				# XXX: need some way of polling
-    result = u.read()
+    then = time.time()                            
+    result = u.read(1.0)	# Takes the CRO a while for this
+    now = time.time()
+    print "CURVE read took %f milliseconds" % ((now - then) * 1000.0)
     data = result[13:]		# Chop off the header
     dattype = numpy.dtype('>h')	# Big endian 16 bit quantity
     ary = numpy.fromstring(data, dtype = dattype)
diff -r 6b360c30eed6 -r 51d1fc44a753 usb488.py
--- a/usb488.py	Wed May 13 17:09:14 2009 +0930
+++ b/usb488.py	Wed May 13 17:17:01 2009 +0930
@@ -195,8 +195,11 @@
             if wrote != len(chunk):
                 raise "Short write, got %d, expected %d" % (wrote, len(chunk))
 
-    def read(self):
-        """Read data from the device"""
+    def read(self, timeout = 0.2):
+        """Read data from the device, waits for up to timeout seconds for each USB transaction"""
+
+        # Mangle into milliseconds
+        _timeout = int(timeout * 1000.0)
 
         # Maximum we accept at once
         # Was 2^31 - 1 but that seems to make things take too long to
@@ -218,12 +221,12 @@
 
             # Send it
             #print "Sending " + str(pkt)
-            wrote = self.handle.bulkWrite(self.bulkoutep, pkt)
+            wrote = self.handle.bulkWrite(self.bulkoutep, pkt, _timeout)
             if wrote != len(pkt):
                 print "Short write, got %d, expected %d" % (wrote, len(pkt))
 
             #print "Reading.."
-            read = self.handle.bulkRead(self.bulkinep, datalen)
+            read = self.handle.bulkRead(self.bulkinep, datalen, _timeout)
             #print "Read %s bytes: %s" % (len(read), str(read))
 
             if read[0] != DEV_DEP_MSG_IN: