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PavelM
Joined: 06 Oct 2021
Posts: 8
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| Modbus RTU |
 Posted: Wed Oct 06, 2021 6:44 am |
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Hello, i'm trying to communicate with HMI Weintek MT6070iH through Modbus RTU. My device is PIC18F87k90 - slave, HMI - master.
PCH Compiler v. 5.101.
Here is my wiring diagram of max485 which I use.
The code is pretty much copy of ex_modbus_slave.c code.
| Code: | #include <main.h>
#define MODBUS_PROTOCOL MODBUS_PROTOCOL_SERIAL
#define MODBUS_BUS SERIAL
#define MODBUS_TYPE MODBUS_TYPE_SLAVE
#define MODBUS_SERIAL_TYPE MODBUS_RTU
#define MODBUS_SERIAL_INT_SOURCE MODBUS_INT_RDA
#define MODBUS_SERIAL_RX_ENABLE PIN_J4
#define MODBUS_SERIAL_ENABLE_PIN PIN_J4
#define MODBUS_SERIAL_BAUD 9600
#define MODBUS_ADDRESS 10
#include "modbus.c"
void main()
{
int8 coils = 0b00000101;
int8 inputs = 0b00001001;
int16 hold_regs[] = {0x8800,0x7700,0x6600,0x5500,0x4400,0x3300,0x2200,0x1100};
int16 input_regs[] = {0x1100,0x2200,0x3300,0x4400,0x5500,0x6600,0x7700,0x8800};
int16 event_count = 0;
setup_adc_ports(NO_ANALOGS);
modbus_init();
while(TRUE)
{
if(!modbus_kbhit())
delay_us(50);
//check address against our address, 0 is broadcast
if((modbus_rx.address == MODBUS_ADDRESS) || modbus_rx.address == 0)
{
switch(modbus_rx.func)
{
//check address against our address, 0 is broadcast
if((modbus_rx.address == MODBUS_ADDRESS) || modbus_rx.address == 0)
{
switch(modbus_rx.func)
{
case FUNC_READ_COILS: //read coils
case FUNC_READ_DISCRETE_INPUT: //read inputs
if(modbus_rx.data[0] || modbus_rx.data[2] ||
modbus_rx.data[1] >= 8 || modbus_rx.data[3]+modbus_rx.data[1] > 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else
{
int8 data;
if(modbus_rx.func == FUNC_READ_COILS)
data = coils>>(modbus_rx.data[1]); //move to the starting coil
else
data = inputs>>(modbus_rx.data[1]); //move to the starting input
data = data & (0xFF>>(8-modbus_rx.data[3])); //0 out values after quantity
if(modbus_rx.func == FUNC_READ_COILS)
modbus_read_coils_rsp(MODBUS_ADDRESS, 0x01, &data);
else
modbus_read_discrete_input_rsp(MODBUS_ADDRESS, 0x01, &data);
event_count++;
}
break;
case FUNC_READ_HOLDING_REGISTERS:
case FUNC_READ_INPUT_REGISTERS:
if(modbus_rx.data[0] || modbus_rx.data[2] ||
modbus_rx.data[1] >= 8 || modbus_rx.data[3]+modbus_rx.data[1] > 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else
{
if(modbus_rx.func == FUNC_READ_HOLDING_REGISTERS)
modbus_read_holding_registers_rsp(MODBUS_ADDRESS,(modbus_rx.data[3]*2),hold_regs+modbus_rx.data[1]);
else
modbus_read_input_registers_rsp(MODBUS_ADDRESS,(modbus_rx.data[3]*2),input_regs+modbus_rx.data[1]);
event_count++;
}
break;
case FUNC_WRITE_SINGLE_COIL: //write coil
if(modbus_rx.data[0] || modbus_rx.data[3] || modbus_rx.data[1] > 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else if(modbus_rx.data[2] != 0xFF && modbus_rx.data[2] != 0x00)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_VALUE);
else
{
if(modbus_rx.data[2] == 0xFF)
bit_set(coils,modbus_rx.data[1]);
else
bit_clear(coils,modbus_rx.data[1]);
modbus_write_single_coil_rsp(MODBUS_ADDRESS,modbus_rx.data[1],((int16)(modbus_rx.data[2]))<<8);
event_count++;
}
break;
case FUNC_WRITE_SINGLE_REGISTER:
if(modbus_rx.data[0] || modbus_rx.data[1] >= 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else
{
hold_regs[modbus_rx.data[1]] = make16(modbus_rx.data[2],modbus_rx.data[3]);
modbus_write_single_register_rsp(MODBUS_ADDRESS,
make16(modbus_rx.data[0],modbus_rx.data[1]),
make16(modbus_rx.data[2],modbus_rx.data[3]));
}
break;
case FUNC_WRITE_MULTIPLE_COILS:
if(modbus_rx.data[0] || modbus_rx.data[2] ||
modbus_rx.data[1] >= 8 || modbus_rx.data[3]+modbus_rx.data[1] > 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else
{
int i,j;
modbus_rx.data[5] = swap_bits(modbus_rx.data[5]);
for(i=modbus_rx.data[1],j=0; i < modbus_rx.data[1]+modbus_rx.data[3]; ++i,++j)
{
if(bit_test(modbus_rx.data[5],j))
bit_set(coils,7-i);
else
bit_clear(coils,7-i);
}
modbus_write_multiple_coils_rsp(MODBUS_ADDRESS,
make16(modbus_rx.data[0],modbus_rx.data[1]),
make16(modbus_rx.data[2],modbus_rx.data[3]));
event_count++;
}
break;
case FUNC_WRITE_MULTIPLE_REGISTERS:
if(modbus_rx.data[0] || modbus_rx.data[2] ||
modbus_rx.data[1] >= 8 || modbus_rx.data[3]+modbus_rx.data[1] > 8)
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_DATA_ADDRESS);
else
{
int i,j;
for(i=0,j=5; i < modbus_rx.data[4]/2; ++i,j+=2)
hold_regs[i] = make16(modbus_rx.data[j],modbus_rx.data[j+1]);
modbus_write_multiple_registers_rsp(MODBUS_ADDRESS,
make16(modbus_rx.data[0],modbus_rx.data[1]),
make16(modbus_rx.data[2],modbus_rx.data[3]));
event_count++;
}
break;
default: //We don't support the function, so return exception
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_FUNCTION);
}
}
}
}
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Not sure about | Quote: | | #define MODBUS_BUS SERIAL |
Haven't found it in libraries and header files.
HMI options - baud rate 9600, parity - even, 8 data bits, 1 stop bit. This options are the same as default options for modbus, I guess.
My test method is to put 1 variable on screen, which reads value from adresses from 0 to 7.
So the panel shows message "PLC not response" and that's it. Any suggestions where to look at? |
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PavelM
Joined: 06 Oct 2021
Posts: 8
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| Posted: Wed Oct 06, 2021 7:43 am |
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Ok, never mind, guess I'm dumb.
Tested with bit variable - LED on screen is blinking with some delay, which i manually put in code, so i guess, I'm trying to work with wrong memory area, need to double check Weintek HMI manual for proper addressing. |
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