Index: trunk/psModules/src/camera/pmFPARead.c
===================================================================
--- trunk/psModules/src/camera/pmFPARead.c	(revision 19046)
+++ trunk/psModules/src/camera/pmFPARead.c	(revision 19246)
@@ -553,4 +553,7 @@
     }
     thisScan -= overlap;
+    if (thisScan < 0) {
+        thisScan = 0;
+    }
     readoutSetThisScan(readout, type, thisScan);