diff --git a/eigerApp/src/eigerDetector.cpp b/eigerApp/src/eigerDetector.cpp
index cf6e6ba..a7163d4 100644
--- a/eigerApp/src/eigerDetector.cpp
+++ b/eigerApp/src/eigerDetector.cpp
@@ -1011,26 +1011,25 @@ void eigerDetector::controlTask (void)
                 getIntegerParam(ADStatus, &adStatus);
             }
         }
-        else // TMExternalSeries or TMExternalEnable
+
+        // Wait for detector to stop acquiring.
+        // Essential for TMExternalSeries or TMExternalEnable,
+        // which have to wait for external action.
+        FLOW("waiting for detector state");
+        string state;
+        for(;;)
         {
-            // The Eiger does not indicate when acquisition is complete.
-            // Wait either until the NumImagesCounter is the expected value or
-            // until there is a manual stop event.
-            int expectedImages = numImages * numTriggers;
-            int numImagesCounter;
-            for(;;)
-            {
-                getIntegerParam(ADNumImagesCounter, &numImagesCounter);
-                if (numImagesCounter >= expectedImages) break;
-                if (mStopEvent.tryWait()) break;
-                unlock();
-                epicsThreadSleep(0.1);
-                lock();
-            }
+            mState->fetch(state);
+            callParamCallbacks();
+            // We must exit this loop without the lock
+            unlock();
+            if (state != "configure" && state != "ready" && state != "acquire") break;
+            if (mStopEvent.wait(0.1)) break;
+            // If we haven't exited yet, grab the lock so we can update the param library
+            lock();
         }
 
         // All triggers issued, disarm the detector
-        unlock();
         status = mApi.disarm();
         lock();
 
@@ -1045,11 +1044,17 @@ void eigerDetector::controlTask (void)
         {
             // Wait FileWriter to go out of the "acquire" state
             FLOW("waiting for FileWriter");
-            string fwAcquire;
-            do
+
+            for(;;)
             {
-                mFWState->get(fwAcquire);
-            }while(fwAcquire == "acquire");
+                string fwAcquire;
+                lock();
+                mFWState->fetch(fwAcquire);
+                callParamCallbacks();
+                unlock();
+                if (fwAcquire != "acquire") break;
+                epicsThreadSleep(0.1);
+            }
             epicsThreadSleep(0.5);
 
             // Request polling task to stop
@@ -1195,8 +1200,6 @@ void eigerDetector::downloadTask (void)
 
         FLOW_ARGS("file=%s", file->name);
 
-        file->refCount = file->parse + file->save;
-
         // Download the file
         if(mApi.getFile(file->name, &file->data, &file->len))
         {
diff --git a/eigerApp/src/eigerDetector.h b/eigerApp/src/eigerDetector.h
index 551c1e9..8831485 100644
--- a/eigerApp/src/eigerDetector.h
+++ b/eigerApp/src/eigerDetector.h
@@ -1,6 +1,7 @@
 #ifndef EIGER_DETECTOR_H
 #define EIGER_DETECTOR_H
 
+#include <atomic>
 #include <map>
 #include <vector>
 
@@ -269,7 +270,11 @@ class eigerDetector : public ADDriver
             mPollDoneEvent, mRestartEvent, mInitializeEvent;
     epicsMessageQueue mPollQueue, mDownloadQueue, mParseQueue, mSaveQueue,
             mReapQueue;
-    bool mPollStop, mPollComplete, mStreamComplete;
+    std::atomic<bool> mPollStop;
+    // Access to this variable is synchronized by mPollQueue and mPollDoneEvent
+    bool mPollComplete;
+    // Access to this variable is synchronized by mStreamEvent and mStreamDoneEvent
+    bool mStreamComplete;
     unsigned int mFrameNumber;
     uid_t mFsUid, mFsGid;
     EigerParamSet mParams;