From e44dd62dbea1f47c13f9883ba57c2485b84c3626 Mon Sep 17 00:00:00 2001
From: Ignacio Martinez Vazquez <ignamv@gmail.com>
Date: Fri, 20 Sep 2013 14:16:36 -0300
Subject: [PATCH] Add GPIBVisaDriver.read_block

Added a function to receive blocks of data in IEEE488.2 # format
---
 lantz/visa.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lantz/visa.py b/lantz/visa.py
index bdd380d..7a37ea7 100644
--- a/lantz/visa.py
+++ b/lantz/visa.py
@@ -207,6 +207,23 @@ def raw_recv(self, size):
 
         return data
 
+    def read_block(self):
+        """Read a block of data in IEEE488.2 # format
+
+        Read a block of data with the format
+        #<D><length><data>
+        <D>: number of digits in <length> (ASCII digit)
+        <length>: number of bytes in <data> (ASCII digits)
+        """
+        header = self.raw_recv(1)
+        if header != b'#':
+            raise Exception('Unexpected block header: {}'.format(
+                            str(header[0])))
+        nlength = int(self.raw_recv(1))
+        length = int(self.raw_recv(nlength))
+        return self.raw_recv(length)
+
+
 class TCPVisaDriver(MessageVisaDriver):
     pass