Allocate four arrays of bits and registers
modbus_mapping_t modbus_mapping_new(int nb_bits, int nb_input_bits, int nb_registers, int nb_input_registers);*
The modbus_mapping_new() function shall allocate four arrays to store bits, input bits, registers and inputs registers. The pointers are stored in modbus_mapping_t structure. All values of the arrays are initialized to zero.
If it isn\(cqt necessary to allocate an array for a specific type of data, you can pass the zero value in argument, the associated pointer will be NULL.
This function is convenient to handle requests in a Modbus server/slave.
The modbus_mapping_new() function shall return the new allocated structure if successful. Otherwise it shall return NULL and set errno.
ENOMEM
Not enough memory
/* The fist value of each array is accessible from the 0 address. */
mb_mapping = modbus_mapping_new(BITS_ADDRESS + BITS_NB,
INPUT_BITS_ADDRESS + INPUT_BITS_NB,
REGISTERS_ADDRESS + REGISTERS_NB,
INPUT_REGISTERS_ADDRESS + INPUT_REGISTERS_NB);
if (mb_mapping == NULL) {
fprintf(stderr, "Failed to allocate the mapping: %s\n",
modbus_strerror(errno));
modbus_free(ctx);
return -1;
}
The libmodbus documentation was written by St\('ephane Raimbault <\m[blue][email protected]\m[]\s-2\u[1]\d\s+2>
mailto:[email protected]