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modbus_read_bits() modbus_read_bits() Name modbus_read_bits - read many bits Synopsis int modbus_read_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest); Description The modbus_read_bits() function shall read the status of the nb bits (coils) to the address addr of the remote device. The result of reading is stored in dest array as unsigned bytes (8 bits) set to TRUE or FALSE. The dest array must be allocated with at least nb * sizeof(uint8_t) bytes. It is the caller's responsibility to ensure the buffer is large enough to hold all the bits to be read. The function uses the Modbus function code 0x01 (read coil status). Return value The function shall return the number of read bits if successful. Otherwise it shall return -1 and set errno. Errors * EINVAL, the ctx or dest argument is NULL, or nb is less than 1. * EMBMDATA, too many bits requested (nb > MODBUS_MAX_READ_BITS). See also * modbus_write_bit <modbus_write_bit.md> * modbus_write_bits <modbus_write_bits.md> modbus_read_bits()
Name | Synopsis | Description | Return value | Errors | See also
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