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new d7cf29f02 industry/nxmodbus: Accept 4-byte RTU frames.
d7cf29f02 is described below
commit d7cf29f02120042f9b1e68f28e068e1e9c47ccf0
Author: raiden00pl <[email protected]>
AuthorDate: Sat Oct 10 15:20:49 2026 +0200
industry/nxmodbus: Accept 4-byte RTU frames.
NXMB_RTU_MIN_FRAME_SIZE was 5, but the shortest valid RTU frame is
unit_id + fc + 2 CRC bytes = 4 bytes, e.g. a Report Server ID (FC17)
request. Such requests were dropped and never answered. Set the
minimum to 4. The ASCII transport already accepts the equivalent
minimum frame (addr + fc + LRC).
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: raiden00pl <[email protected]>
---
industry/nxmodbus/transport/nxmb_serial.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/industry/nxmodbus/transport/nxmb_serial.c
b/industry/nxmodbus/transport/nxmb_serial.c
index 679e0d597..543ed64a3 100644
--- a/industry/nxmodbus/transport/nxmb_serial.c
+++ b/industry/nxmodbus/transport/nxmb_serial.c
@@ -48,7 +48,9 @@
* Pre-processor Definitions
****************************************************************************/
-#define NXMB_RTU_MIN_FRAME_SIZE 5
+/* Minimum wire frame: unit_id + fc + 2 CRC bytes (e.g. FC17 request) */
+
+#define NXMB_RTU_MIN_FRAME_SIZE 4
/* Wire frame: unit_id + fc + data + 2 CRC bytes */
