diff --git a/ADHamaApp/src/hama.cpp b/ADHamaApp/src/hama.cpp
index 7f7d396..49cf33f 100644
--- a/ADHamaApp/src/hama.cpp
+++ b/ADHamaApp/src/hama.cpp
@@ -1644,19 +1644,19 @@ asynStatus Hama::writeFloat64(asynUser *pasynUser, epicsFloat64 value){
         printf("[DEBUG]::function ADAcquireTime from camera: %f\n", value);
         
         int trigger_mode = 0;
-        getIntegerParam(hTriggerSource, &trigger_mode);
-        m_err = dcamprop_getvalue(m_hdcam, DCAM_IDPROP_EXPOSURETIME, &dvalue);
+        double acquire_period = 0;
+        status = getDoubleParam(ADAcquirePeriod, &acquire_period);
+        status = getIntegerParam(hTriggerSource, &trigger_mode);
 
         if (trigger_mode == DCAMPROP_TRIGGERSOURCE__EXTERNAL) {
-            if (dvalue <= value) status = asynError;
+            if (value >= acquire_period) status = asynError;
+            else {
+                status = setFeature(DCAM_IDPROP_EXPOSURETIME, value);
+            }
         }
 
         else {
             status = setFeature(DCAM_IDPROP_EXPOSURETIME, value);
-            m_err = dcamprop_getvalue(m_hdcam, DCAM_IDPROP_EXPOSURETIME, &dvalue);
-
-            double acquire_period = 0;
-            status = getDoubleParam(ADAcquirePeriod, &acquire_period);
             if (value >= acquire_period) {
                 status = setFeature(DCAM_IDPROP_TRIGGERSOURCE, DCAMPROP_TRIGGERSOURCE__INTERNAL);
                 status = setIntegerParam(hTriggerSource, DCAMPROP_TRIGGERSOURCE__INTERNAL);