got query_DTC returning cleanly with obdsim

Brendan Whitfield · Brendan Whitfield · commit b2e43b35a785 · 2015-03-01T20:48:19.000-05:00
diff --git a/obd/commands.py b/obd/commands.py
@@ -160,7 +160,7 @@
 
 __mode3__ = [
 	#                  sensor name                          description                   mode  cmd bytes       decoder
-	OBDCommand("GET_DTC"                    , "Get DTCs"                                , "03", "" , 6, noop                   , True),
+	OBDCommand("GET_DTC"                    , "Get DTCs"                                , "03", "" , 6, dtc_frame              , True),
 ]
 
 __mode4__ = [
diff --git a/obd/decoders.py b/obd/decoders.py
@@ -343,24 +343,36 @@ def describeCode(code):
 '''
 
 # converts 2 bytes of hex into a DTC code
-def dtc(_hex):
+def single_dtc(_hex):
+
+	if _hex == "0000":
+		return None
+
 	dtc = ""
-	bits = bitstring(_hex[0])
+	bits = bitstring(_hex[0], 4)
 
 	dtc += ['P', 'C', 'B', 'U'][unbin(bits[0:2])]
 	dtc += str(unbin(bits[2:4]))
 	dtc += _hex[1:4]
 
-	return (dtc, Unit.NONE)
+	return dtc
 
 # converts a frame of 2-byte DTCs into a list of DTCs
+# example input = 01 04 80 03 41 23
+#                 [DTC] [DTC] [DTC]
 def dtc_frame(_hex):
 	codes = []
-	for n in range(3):
+	for n in range(0, 12, 4):
+		dtc = single_dtc(_hex[n:n+4])
+
+		if dtc is not None:
+
+			# pull a description if we have one
+			if dtc in DTC:
+				dtc += ": %s" % DTC[dtc]
+			else:
+				dtc += ": unknown error code"
 
-		start = 4 * n
-		end = start + 4
-		
-		codes.append(dtc(_hex[start:end]))
+			codes.append(dtc)
 
 	return (codes, Unit.NONE)
diff --git a/obd/elm327.py b/obd/elm327.py
@@ -287,6 +287,7 @@ def __send(self, cmd, delay=None):
 		self.__write(cmd)
 
 		if delay is not None:
+			debug("wait: %d seconds" % delay)
 			time.sleep(delay)
 
 		return self.__read()
diff --git a/obd/obd.py b/obd/obd.py
@@ -184,14 +184,25 @@ def query(self, c, force=False):
 	def query_DTC(self):
 		""" read all DTCs """
 
-		n = self.query(commands.STATUS).value.DTC_count;
+		status = self.query(commands.STATUS);
+
+		if status.is_null():
+			debug("Failed to retrieve number of DTCs", True)
+			return []
+
+		n = status.value.DTC_count
 		n = n if (n < 128) else 0  # if this number is over 128, it's invalid
 
 		codes = [];
 
 		while n > 0:
-			current_codes = self.query(commands.GET_DTC).value
-			codes += current_codes
-			n -= len(current_codes)
+			get_dtc = self.query(commands.GET_DTC)
+
+			if get_dtc.is_null():
+				debug("Failed to retrieve DTCs", True)
+				break
+
+			codes += get_dtc.value
+			n -= len(get_dtc.value)
 
 		return codes

Original file line number	Diff line number	Diff line change
`@@ -160,7 +160,7 @@`
`160`	`160`
`161`	`161`	`__mode3__ = [`
`162`	`162`	`# sensor name description mode cmd bytes decoder`
`163`		`- OBDCommand("GET_DTC" , "Get DTCs" , "03", "" , 6, noop , True),`
	`163`	`+ OBDCommand("GET_DTC" , "Get DTCs" , "03", "" , 6, dtc_frame , True),`
`164`	`164`	`]`
`165`	`165`
`166`	`166`	`__mode4__ = [`