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epsilonrtepsilonrt
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‎src/Modbus.cpp

Lines changed: 107 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
11
/*
22
Modbus.cpp - Source for Modbus Base Library
33
Copyright (C) 2014 André Sarmento Barbosa
4+
Copyright (C) 2023 Pascal JEAN aka epsilonrt
45
*/
56
#include "Modbus.h"
67

@@ -73,6 +74,7 @@ word Modbus::reg (word address) {
7374
}
7475
}
7576

77+
// INLINE --------------------
7678
void Modbus::addHreg (word offset, word value) {
7779
this->addReg (offset + 40001, value);
7880
}
@@ -132,6 +134,7 @@ word Modbus::ireg (word offset) {
132134
return reg (offset + 30001);
133135
}
134136
#endif
137+
// INLINE --------------------
135138

136139

137140
void Modbus::receivePDU (byte * frame) {
@@ -203,6 +206,17 @@ void Modbus::exceptionResponse (byte fcode, byte excode) {
203206
_reply = MB_REPLY_NORMAL;
204207
}
205208

209+
/*
210+
Func 17: Report Server ID
211+
Request
212+
Function code 1 Byte 0x11
213+
Response
214+
Function code 1 Byte 0x11
215+
Byte Count 1 Byte
216+
Server ID device specific
217+
Run Indicator Status 1 Byte 0x00 = OFF, 0xFF = ON
218+
Additional Data
219+
*/
206220
void Modbus::reportServerId() {
207221
//Clean frame buffer
208222
free (_frame);
@@ -241,6 +255,18 @@ int Modbus::setAdditionalServerData (const char data[]) {
241255
return 0;
242256
}
243257

258+
/*
259+
Func 03: Read Holding Registers
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Request
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Function code 1 Byte 0x03
262+
Starting Address 2 Bytes 0x0000 to 0xFFFF
263+
Quantity of Registers 2 Bytes 1 to 125 (0x7D)
264+
Response
265+
Function code 1 Byte 0x03
266+
Byte count 1 Byte 2 x N*
267+
Register value N* x 2 Bytes
268+
*N = Quantity of Registers
269+
*/
244270
void Modbus::readRegisters (word startreg, word numregs) {
245271
//Check value (numregs)
246272
if (numregs < 0x0001 || numregs > 0x007D) {
@@ -288,6 +314,16 @@ void Modbus::readRegisters (word startreg, word numregs) {
288314
_reply = MB_REPLY_NORMAL;
289315
}
290316

317+
/* Func 06: Write Single Register
318+
Request
319+
Function code 1 Byte 0x06
320+
Register Address 2 Bytes 0x0000 to 0xFFFF
321+
Register Value 2 Bytes 0x0000 to 0xFFFF
322+
Response
323+
Function code 1 Byte 0x06
324+
Register Address 2 Bytes 0x0000 to 0xFFFF
325+
Register Value 2 Bytes 0x0000 to 0xFFFF
326+
*/
291327
void Modbus::writeSingleRegister (word reg, word value) {
292328
//No necessary verify illegal value (EX_ILLEGAL_VALUE) - because using word (0x0000 - 0x0FFFF)
293329
//Check Address and execute (reg exists?)
@@ -302,9 +338,22 @@ void Modbus::writeSingleRegister (word reg, word value) {
302338
return;
303339
}
304340

305-
_reply = MB_REPLY_ECHO;
341+
_reply = MB_REPLY_ECHO; // reply with received frame
306342
}
307343

344+
/* Func 16: Write Multiple registers
345+
Request
346+
Function code 1 Byte 0x10
347+
Starting Address 2 Bytes 0x0000 to 0xFFFF
348+
Quantity of Registers 2 Bytes 0x0001 to 0x007B
349+
Byte Count 1 Byte 2 x N*
350+
Registers Value N* x 2 Bytes value
351+
*N = Quantity of Registers
352+
Response
353+
Function code 1 Byte 0x10
354+
Starting Address 2 Bytes 0x0000 to 0xFFFF
355+
Quantity of Registers 2 Bytes 1 to 123 (0x7B)
356+
*/
308357
void Modbus::writeMultipleRegisters (byte * frame, word startreg, word numoutputs, byte bytecount) {
309358
//Check value
310359
if (numoutputs < 0x0001 || numoutputs > 0x007B || bytecount != 2 * numoutputs) {
@@ -347,6 +396,17 @@ void Modbus::writeMultipleRegisters (byte * frame, word startreg, word numoutput
347396
}
348397

349398
#ifndef USE_HOLDING_REGISTERS_ONLY
399+
/* Func 01: Read Coils
400+
Request
401+
Function code 1 Byte 0x01
402+
Starting Address 2 Bytes 0x0000 to 0xFFFF
403+
Quantity of coils 2 Bytes 1 to 2000 (0x7D0)
404+
Response
405+
Function code 1 Byte 0x01
406+
Byte count 1 Byte N*
407+
Coil Status n Byte n = N or N+1
408+
*N = Quantity of Outputs / 8, if the remainder is different of 0 -> N = N+1
409+
*/
350410
void Modbus::readCoils (word startreg, word numregs) {
351411
//Check value (numregs)
352412
if (numregs < 0x0001 || numregs > 0x07D0) {
@@ -407,6 +467,18 @@ void Modbus::readCoils (word startreg, word numregs) {
407467
_reply = MB_REPLY_NORMAL;
408468
}
409469

470+
/* Func 02: Read Discrete Inputs
471+
Request
472+
Function code 1 Byte 0x02
473+
Starting Address 2 Bytes 0x0000 to 0xFFFF
474+
Quantity of Inputs 2 Bytes 1 to 2000 (0x7D0)
475+
Response
476+
Function code 1 Byte 0x02
477+
Byte count 1 Byte N*
478+
Input Status N* x 1 Byte
479+
*N = Quantity of Inputs / 8 if the remainder is different of 0  N = N+1
480+
Error
481+
*/
410482
void Modbus::readInputStatus (word startreg, word numregs) {
411483
//Check value (numregs)
412484
if (numregs < 0x0001 || numregs > 0x07D0) {
@@ -464,6 +536,17 @@ void Modbus::readInputStatus (word startreg, word numregs) {
464536
_reply = MB_REPLY_NORMAL;
465537
}
466538

539+
/* Func 04: Read Input Registers
540+
Request
541+
Function code 1 Byte 0x04
542+
Starting Address 2 Bytes 0x0000 to 0xFFFF
543+
Quantity of Input Registers 2 Bytes 0x0001 to 0x007D
544+
Response
545+
Function code 1 Byte 0x04
546+
Byte count 1 Byte 2 x N*
547+
Input Registers N* x 2 Bytes
548+
*N = Quantity of Input Registers
549+
*/
467550
void Modbus::readInputRegisters (word startreg, word numregs) {
468551
//Check value (numregs)
469552
if (numregs < 0x0001 || numregs > 0x007D) {
@@ -510,6 +593,16 @@ void Modbus::readInputRegisters (word startreg, word numregs) {
510593
_reply = MB_REPLY_NORMAL;
511594
}
512595

596+
/* Func 05: Write Single Coil
597+
Request
598+
Function code 1 Byte 0x05
599+
Output Address 2 Bytes 0x0000 to 0xFFFF
600+
Output Value 2 Bytes 0x0000 or 0xFF00
601+
Response
602+
Function code 1 Byte 0x05
603+
Output Address 2 Bytes 0x0000 to 0xFFFF
604+
Output Value 2 Bytes 0x0000 or 0xFF00
605+
*/
513606
void Modbus::writeSingleCoil (word reg, word status) {
514607
//Check value (status)
515608
if (status != 0xFF00 && status != 0x0000) {
@@ -529,9 +622,21 @@ void Modbus::writeSingleCoil (word reg, word status) {
529622
return;
530623
}
531624

532-
_reply = MB_REPLY_ECHO;
625+
_reply = MB_REPLY_ECHO; // reply with received frame
533626
}
534627

628+
/* Func 15: Write Multiple Coils
629+
Request
630+
Function code 1 Byte 0x0F
631+
Starting Address 2 Bytes 0x0000 to 0xFFFF
632+
Quantity of Outputs 2 Bytes 0x0001 to 0x07B0
633+
Byte Count 1 Byte N* (Quantity of Outputs / 8, if the remainder is different of 0 -> N = N+1)
634+
Outputs Value N* x 1 Byte
635+
Response
636+
Function code 1 Byte 0x0F
637+
Starting Address 2 Bytes 0x0000 to 0xFFFF
638+
Quantity of Outputs 2 Bytes 0x0001 to 0x07B0
639+
*/
535640
void Modbus::writeMultipleCoils (byte * frame, word startreg, word numoutputs, byte bytecount) {
536641
//Check value
537642
word bytecount_calc = numoutputs / 8;

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