diff --git a/src/el734Axis.cpp b/src/el734Axis.cpp
index 5fda007..b40c2aa 100644
--- a/src/el734Axis.cpp
+++ b/src/el734Axis.cpp
@@ -681,6 +681,14 @@ asynStatus el734Axis::readEncoderType() {
     case 4:
         setAxisParamChecked(this, encoderType, AbsoluteEncoder);
         break;
+    default:
+        asynPrint(pC_->pasynUser(), ASYN_TRACE_ERROR,
+                  "Controller \"%s\", axis %d  => %s, line %d\nUnknown encoder "
+                  "type %d. Please call the support.\n",
+                  pC_->portName, axisNo_, __PRETTY_FUNCTION__, __LINE__,
+                  encoder_type);
+        setAxisParamChecked(this, motorStatusProblem, true);
+        return asynError;
     }
     return asynSuccess;
 }