Index: trunk/Mars/mcore/PixelMap.h
===================================================================
--- trunk/Mars/mcore/PixelMap.h	(revision 17008)
+++ trunk/Mars/mcore/PixelMap.h	(revision 17009)
@@ -39,4 +39,5 @@
     int hw() const    { return pixel()+patch()*9+board()*36+crate()*360; }
     int group() const { return pixel()>3; }
+    int count() const { return pixel()>3 ? 5 : 4; }
     int hv() const    { return hv_channel+hv_board*32; }
 
@@ -201,8 +202,8 @@
     int   hv_channel;          /// Bias supply channel
     float Vnom;                /// Channel bias voltage nominal
-    float Voff;                /// Channel bias voltage offset
-    float Vslope;              /// Channel bias voltage slope
-
-    BiasMapEntry() : hv_board(-1) { }
+    float Voff;                /// Channel bias voltage offset [V]
+    float Vslope;              /// Channel bias voltage slope  [Ohm]
+
+    BiasMapEntry() : hv_board(-1), Voff(0), Vslope(90000) { }
 
     int hv() const { return hv_channel+hv_board*32; }
@@ -270,5 +271,5 @@
 #ifdef __EXCEPTIONS
         if (l!=416)
-            throw std::runtime_error("Number of lines read from "+fname+" does not match 416.");
+            throw std::runtime_error("Number of lines ("+std::to_string(l)+") read from "+fname+" does not match 416.");
 
         if (size()!=416)