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CDE_modicaon
Joined: 11 Dec 2013
Posts: 7
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| modscan32 with PIC18F2550 |
 Posted: Thu Dec 12, 2013 12:04 am |
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we want to implement a modbus communication b/w Modbus32 and Pic controller. I am using PCWHD compiler version 4.093. Plz help me how to implement and let me know which example should be used:
Ex_modbus.c
Ex_modbus_slave
I am using FTDI cable for communication b/w PC (modscan32) to PIC controller. Plz reply.
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Gabriel
Joined: 03 Aug 2009
Posts: 1067
Location: Panama
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| Posted: Thu Dec 12, 2013 7:59 am |
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you need to decide if you are going to use modbus RTU or modbus ACII.
then you need to decide if your making a slave or a master...
Then you need to look in you examples/Driver folders, CCS provides all you need.
the entire modbus Driver/example is (at least in the later compilers) made of 7 files total.
you need to configure the example by selecting the right defines on modbus.c
read the file headers of the drivers. CCS provides some kind of isntructions on how to set it up.
Modbus RTU/ASCII run over RS485... I dont know if modscan32 will work with FTDI coms since its made for RS232... asuming you have the FTDI cable like from sparkfun.
G.
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CCS PCM 5.078 & CCS PCH 5.093 |
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CDE_modicaon
Joined: 11 Dec 2013
Posts: 7
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| modscan32 with PIC18F2550 |
| Posted: Thu Dec 12, 2013 9:50 am |
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Thank you very much for your reply....
My aim is to communicate b/w pic18F2550 (as a slave) with S7-1200 Siemens PLC (as a master).
I read the EX_modbus.c and EX_modbus_Slave.c which is given in PICC compiler.
If i assume that FTDI cable is working with Pic, then what is the next step ? How to start slave programming ? How to read holding register if master polling ?
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CDE_modicaon
Joined: 11 Dec 2013
Posts: 7
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| Re: modscan32 with PIC18F2550 |
| Posted: Fri Dec 13, 2013 3:26 am |
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plz check the code which i am using for PIC18F2550 (as a slave).
| Code: |
#include <18F2550.h>
#use delay(internal=8MHz)
#fuses HS,NOLVP,NOWDT,NOBROWNOUT,PROTECT, PUT
#define MODBUS_TYPE MODBUS_TYPE_SLAVE
#define MODBUS_SERIAL_RX_BUFFER_SIZE 40
#define MODBUS_SERIAL_BAUD 9600
#ifndef USE_WITH_PC
#define MODBUS_SERIAL_INT_SOURCE MODBUS_INT_EXT
#define MODBUS_SERIAL_TX_PIN PIN_A5 // Data transmit pin(FTDI CABLE)
#define MODBUS_SERIAL_RX_PIN PIN_A4 // Data receive pin(FTDI CABLE)
#define MODBUS_SERIAL_INT_SOURCE MODBUS_INT_RDA
#define USE_WITH_PC 1
#include "modbus.c"
#define MODBUS_ADDRESS 0x05
/*This function may come in handy for you since MODBUS uses MSB first.*/
int8 swap_bits(int8 c)
{
return ((c&1)?128:0)|((c&2)?64:0)|((c&4)?32:0)|((c&8)?16:0)|((c&16)?8:0)
|((c&32)?4:0)|((c&64)?2:0)|((c&128)?1:0);
}
void main()
{
int i,one_time=0;
int8 coils1 = 0b11111111;
int8 inputs = 0b11111111;
int poll=0;
setup_timer_0(RTCC_INTERNAL);
modbus_init();
while(1)
{
output_toggle(PIN_C2);
if(one_time==1)
{
one_time=0;
if(bit_test (coils1, 0)) output_bit(PIN_B4,1); else output_bit(PIN_B4,0);
if(bit_test (coils1, 1)) output_bit(PIN_B3,1); else output_bit(PIN_B3,0);
if(bit_test (coils1, 2)) output_bit(PIN_C0,1); else output_bit(PIN_C0,0);
if(bit_test (coils1, 3)) output_bit(PIN_C1,1); else output_bit(PIN_C1,0);
}
poll++;
if(modbus_kbhit()!=1)
{
}
else
{
poll=0;
//check address against our address, 0 is broadcast
if((modbus_rx.address == MODBUS_ADDRESS) || modbus_rx.address == 0)
{
switch(modbus_rx.func)
{
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(coils1,7-i);
else
bit_clear(coils1,7-i);
}
one_time=1;
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]));
}
break;
default: //We don't support the function, so return exception
modbus_exception_rsp(MODBUS_ADDRESS,modbus_rx.func,ILLEGAL_FUNCTION);
}
}
}
} //while
} //main |
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temtronic
Joined: 01 Jul 2010
Posts: 9246
Location: Greensville,Ontario
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| Posted: Fri Dec 13, 2013 7:51 am |
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comment: Do not 'assume' the FTDI module is working with PIC.
Cut code for a simple 'loopback' program(there's an example in the FAQ section) and CONFIRM the module and PIC are operational. It's easy to get one fuse wrong, PIC won't run and you 'think' it's your MODBUS code...
Once you've confirmed the PIC and FTDI are good , then proceed with your code.Small steps!
hth
jay |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19553
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| Posted: Fri Dec 13, 2013 9:28 am |
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| There are _two_ defines for the MODBUS interrupt source. One using INT_EXT, and a software UART, and one using INT_RDA and the hardware UART. Both are present in the posted code.... |
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