Added sleep after write commands

See comment in writeRead for explanation.

src/turboPmacController.cpp

@@ -207,7 +207,6 @@ asynStatus turboPmacController::writeRead(int axisNo, const char *command,
     // Definition of local variables.
     asynStatus status = asynSuccess;
     asynStatus timeoutStatus = asynSuccess;
-    // char fullCommand[MAXBUF_] = {0};
     char drvMessageText[MAXBUF_] = {0};
     char modResponse[MAXBUF_] = {0};
     int motorStatusProblem = 0;
@@ -255,6 +254,22 @@ asynStatus turboPmacController::writeRead(int axisNo, const char *command,
         pasynOctetSyncIOipPort(), command, commandLength, response, MAXBUF_,
         pTurboPmacC_->comTimeout, &nbytesOut, &nbytesIn, &eomReason);
 
+    /*
+    If sth. is written to the controller, it needs some time to process the
+    command. However, the controller returns the acknowledgment via
+    pasynOctetSyncIO->writeRead immediately, signalling to the driver that it is
+    ready to receive the next command. In practice, this can result in commands
+    getting discarded on the driver side or in bringing the driver in undefined
+    states (e.g. stuck in status 1).
+
+    To prevent this, we wait for 20 ms after a write command to give the
+    controller enough time to process everything. A write command can be
+    identified by looking for the equal sign.
+    */
+    if (strchr(command, '=')) {
+        usleep(20000);
+    }
+
     msgPrintControlKey comKey =
         msgPrintControlKey(portName, axisNo, __PRETTY_FUNCTION__, __LINE__);