diff --git a/doc/nodes/CBuilder.md b/doc/nodes/CBuilder.md
index 5066b153d..360c85bd2 100644
--- a/doc/nodes/CBuilder.md
+++ b/doc/nodes/CBuilder.md
@@ -6,5 +6,6 @@ Simple CBuilder control blocks can be executed in VILLASnode.
 Every CBuilder component is represented as a node in the VILLAS concept.
 
 The aforementioned real-time code is written in a dialect of the C programming language.
-This allows the cross-compilation of CBuilder code for VILLASnode.
-The user only has to obey to the specifc structure of CBuilder code. 
\ No newline at end of file
+This enables easy cross-compilation of CBuilder code for VILLASnode.
+The user only has to obey to the specifc structure of CBuilder code.
+The file models/simple_circuit.c is an example for this structure.
diff --git a/src/pipe.c b/src/pipe.c
index 894733de5..15ed30a91 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -154,9 +154,13 @@ static void * recv_loop(void *ctx)
 
 	for (;;) {
 		int recv = node_read(node, smps, node->vectorize);
+		struct timespec now = time_now();
 		for (int i = 0; i < recv; i++) {
 			struct sample *s = smps[i];
 
+			if (s->ts.received.tv_sec == -1 || s->ts.received.tv_sec == 0)
+				s->ts.received = now;
+
 			sample_fprint(stdout, s, SAMPLE_ALL);
 			fflush(stdout);
 		}