138 lines
4.0 KiB
C
138 lines
4.0 KiB
C
/*---------------------------------------------------------------------------
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M O D B U S T C P . C
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Paul Barron, January 2008
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RTU Modbus functions designed for use with the WEST4100 Temperature Controller.
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If another modbus device is required at ANSTO sections of this code will need
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to be modified.
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MBAP: Modbus Application Protocol Header
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PDU: Protocol Data Unit
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Modbus TCP Packet Format
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| MBAP | PDU |
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|Transact Identifier|Protocol Identifier|Length Field|Unit ID|Funct Code|Data|
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| 2 Bytes | 2 Bytes | 2 Bytes | 1 Byte| 1 Byte | n |
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Paul Barron, January 2008
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----------------------------------------------------------------------------*/
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "obdes.h"
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#include "conman.h"
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#include "rs232controller.h"
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#include "modbustcp.h"
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/*-------------------------------------------------------------------------*/
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int ModbusTCPException(unsigned char *response);
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int MsgGenModbusTCP(unsigned char *ModbusMsg, int ModbusMsgLength, unsigned char *TcpPacket,
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int *TcpPacketLength)
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{
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unsigned char MBAPbyte1 = 1, MBAPbyte2 = 1;
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unsigned char lengthByte1, lengthByte2;
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int index;
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// Check if Device Address is Valid. This is based on RS485 having up to
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// 32 devices, since we currently only have one device this won't be a problem.
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if ((ModbusMsg[0] > 32) || (ModbusMsg[0] < 1))
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{
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printf("Error: Modbus Address out of Range: %X\n",ModbusMsg[0]);
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return MODBUSTCP_BadDataAddress;
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}
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// Check if Function code is Valid
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if ((ModbusMsg[1] > 16) || (ModbusMsg[1] < 1))
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{
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printf("Error: Modbus Function Code Invalid: %X\n",ModbusMsg[1]);
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return MODBUSTCP_BadFunction;
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}
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// Calculate Legth Field
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// Length should never be greater than 255 but just in case.
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if ((ModbusMsgLength)>255){
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lengthByte1=ModbusMsgLength/255;
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lengthByte2=ModbusMsgLength%255;
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}
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else{
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lengthByte1=0;
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lengthByte2=ModbusMsgLength;
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}
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sprintf((char *)TcpPacket,"%c%c%c%c%c%c",MBAPbyte1,MBAPbyte2,0,0,lengthByte1,lengthByte2);
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for(index=0;index<=ModbusMsgLength;index++)sprintf((char *)&TcpPacket[index+6],"%c",ModbusMsg[index]);
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*TcpPacketLength=ModbusMsgLength+6;
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return 1;
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}
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/*-------------------------------------------------------------------------*/
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int transactModbusTCP(prs232 self, unsigned char *query, int queryLength, unsigned char *response, int responseLength)
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{
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unsigned char TCPquery[40];
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int iRet, index, TCPqueryLength;
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// Generate the TCP message
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iRet=MsgGenModbusTCP(query,queryLength,TCPquery,&TCPqueryLength);
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// Send the message and Read the reply
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memset(response,0,responseLength); // puts zeros in reply up until reply length
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if ((iRet=transactRS232(self,TCPquery,/*strlen(pCommand)*/12,response,20))<=0)
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{
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printf("Comms error!\n");
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return iRet; // Comms problem
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}
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// Check that the response transact and protocol identifier are the same
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if( (strncmp((char *)TCPquery,(char *)response,3)) == 0)
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{
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// Check that there is not a modbus error, see page 98 from WEST4100 User manual.
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if ( response[7] > 0x80 )
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{
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iRet=ModbusTCPException(response);
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return iRet;
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}
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else
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{
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// Return the modbus response minus the TCP Header
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for(index=0;index<6;index++)
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response[index]=response[index+6];
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return 1;
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}
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return 1; // Success
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}
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return MODBUSTCP_TCPError;
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}
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/*-------------------------------------------------------------------------*/
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int ModbusTCPException(unsigned char *response)
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{
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if(response[8] == 0x01){
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printf("Exception Code 01h: Illegal Function\n");
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return MODBUSTCP_IllegalFunction;
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}else if(response[8] == 0x02){
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printf("Exception Code 02h: Illegal Data Address\n");
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return MODBUSTCP_IllegalDataAddress;
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}else if(response[8] == 0x03){
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printf("Exception Code 03h: Illegal Data Value\n");
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return MODBUSTCP_IllegalDataValue;
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}else{
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printf("Error code is greater than 81h, 82h or 83h\n");
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return MODBUSTCP_UnsupportedError;
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}
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}
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/*-------------------------------------------------------------------------*/
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