Peter M. Groen / libmodbus

Commit cfeca264b4a5bbfdcfe7e2d4ddba9093b88e75f1

Authored by Pascal Bach
Committed by GitHub
1 parent 27b90ded

address check in single register / coil responses added (#463) 

Address check in single register / coil responses added

According to Modbus standard the address of single register / coils request and response must match

Co-authored-by: Heinrich Gsponer <heinrich.gsponer@siemens.com>
Inline Side-by-side
Showing 1 changed file with 22 additions and 2 deletions
src/modbus.c
  View file @cfeca26
@@ -555,6 +555,8 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req, @@ -555,6 +555,8 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req,
555 function < 0x80) { 555 function < 0x80) {
556 int req_nb_value; 556 int req_nb_value;
557 int rsp_nb_value; 557 int rsp_nb_value;
  558 + int resp_addr_ok = TRUE;
  559 + int resp_data_ok = TRUE;
558 560
559 /* Check function code */ 561 /* Check function code */
560 if (function != req[offset]) { 562 if (function != req[offset]) {
@@ -591,6 +593,10 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req, @@ -591,6 +593,10 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req,
591 break; 593 break;
592 case MODBUS_FC_WRITE_MULTIPLE_COILS: 594 case MODBUS_FC_WRITE_MULTIPLE_COILS:
593 case MODBUS_FC_WRITE_MULTIPLE_REGISTERS: 595 case MODBUS_FC_WRITE_MULTIPLE_REGISTERS:
  596 + /* address in request and response must be equal */
  597 + if ((req[offset + 1] != rsp[offset + 1]) || (req[offset + 2] != rsp[offset + 2])) {
  598 + resp_addr_ok = FALSE;
  599 + }
594 /* N Write functions */ 600 /* N Write functions */
595 req_nb_value = (req[offset + 3] << 8) + req[offset + 4]; 601 req_nb_value = (req[offset + 3] << 8) + req[offset + 4];
596 rsp_nb_value = (rsp[offset + 3] << 8) | rsp[offset + 4]; 602 rsp_nb_value = (rsp[offset + 3] << 8) | rsp[offset + 4];
@@ -599,17 +605,31 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req, @@ -599,17 +605,31 @@ static int check_confirmation(modbus_t *ctx, uint8_t *req,
599 /* Report slave ID (bytes received) */ 605 /* Report slave ID (bytes received) */
600 req_nb_value = rsp_nb_value = rsp[offset + 1]; 606 req_nb_value = rsp_nb_value = rsp[offset + 1];
601 break; 607 break;
  608 + case MODBUS_FC_WRITE_SINGLE_COIL:
  609 + case MODBUS_FC_WRITE_SINGLE_REGISTER:
  610 + /* address in request and response must be equal */
  611 + if ((req[offset + 1] != rsp[offset + 1]) || (req[offset + 2] != rsp[offset + 2])) {
  612 + resp_addr_ok = FALSE;
  613 + }
  614 + /* data in request and response must be equal */
  615 + if ((req[offset + 3] != rsp[offset + 3]) || (req[offset + 4] != rsp[offset + 4])) {
  616 + resp_data_ok = FALSE;
  617 + }
  618 + /* 1 Write functions & others */
  619 + req_nb_value = rsp_nb_value = 1;
  620 + break;
602 default: 621 default:
603 /* 1 Write functions & others */ 622 /* 1 Write functions & others */
604 req_nb_value = rsp_nb_value = 1; 623 req_nb_value = rsp_nb_value = 1;
  624 + break;
605 } 625 }
606 626
607 - if (req_nb_value == rsp_nb_value) { 627 + if ((req_nb_value == rsp_nb_value) && (resp_addr_ok == TRUE) && (resp_data_ok == TRUE)) {
608 rc = rsp_nb_value; 628 rc = rsp_nb_value;
609 } else { 629 } else {
610 if (ctx->debug) { 630 if (ctx->debug) {
611 fprintf(stderr, 631 fprintf(stderr,
612 - "Quantity not corresponding to the request (%d != %d)\n", 632 + "Received data not corresponding to the request (%d != %d)\n",
613 rsp_nb_value, req_nb_value); 633 rsp_nb_value, req_nb_value);
614 } 634 }
615 635