diff --git a/src/hwapi.cpp b/src/hwapi.cpp
index 71fc7cb..26fc307 100644
--- a/src/hwapi.cpp
+++ b/src/hwapi.cpp
@@ -188,7 +188,7 @@ hwapi::DownloadResult hwapi::sendNextAddress(int bNum) const {
         qDebug() << "addr-block" << bNum << "...";
         while (noAnswerCount <= 250) {
             bl_sendAddress(bNum);
-            std::this_thread::sleep_for(std::chrono::milliseconds(10));
+            std::this_thread::sleep_for(std::chrono::milliseconds(100));
             DownloadResult const res = sendStatus(bl_wasSendingAddOK());
             if (res != DownloadResult::NOP) {
                 if (res == DownloadResult::ERROR) {
@@ -246,24 +246,24 @@ hwinf::DownloadResult hwapi::sendNextDataBlock(QByteArray const &binary,
 }
 
 hwinf::DownloadResult hwapi::dc_downloadBinary(QByteArray const &b) const {
-
     int const nBlocks = (((b.size())%64)==0) ? (b.size()/64) : (b.size()/64)+1;
 
     qInfo() << "total number of bytes to send to dc" << b.size();
     qInfo() << "total number of blocks to send to dc" << nBlocks;
 
-    for (int blockNumber = 0; blockNumber < nBlocks; ++blockNumber) {
-        DownloadResult res = sendNextAddress(blockNumber);
-        if (res == DownloadResult::NOP) {            // no address had to be
-            res = sendNextDataBlock(b, blockNumber); // sent, so send next block
-        }                                            // as data block
-        if (res != DownloadResult::OK) {
-            return res;
+    int bNum = 0;
+    DownloadResult res = DownloadResult::OK;
+    while (res != DownloadResult::ERROR &&  bNum < nBlocks) {
+        if ((res = sendNextAddress(bNum)) != DownloadResult::ERROR) {
+            if ((res = sendNextDataBlock(b, bNum)) != DownloadResult::ERROR) {
+                bNum += 1;
+            }
         }
     }
-
-    bl_sendLastBlock();
-    return DownloadResult::OK;
+    if (res != DownloadResult::ERROR) {
+        bl_sendLastBlock();
+    }
+    return res;
 }
 
 bool hwapi::startBootloader() const {
@@ -2960,7 +2960,6 @@ void hwapi::bl_sendLastBlock(void) const
 
     len=dcBL_writeLastPage(buf);
     sendWRcmd_setSendBlock160(len, buf);
-
 }
 
 uint8_t hwapi::bl_wasSendingDataOK(void) const