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LibFINS API Reference – finslib_memory_area_write_bit()

finslib_memory_area_write_bit( sys, start, data, num_bit );


Parameter Type Description
sys struct fins_sys_tp * A pointer to a structure with the FINS context
start const char * An ASCII string describing the first memory element to write
data const bool * Pointer to the buffer where the data to be written is located
num_bit size_t The number of bits to write

Return Value

Type Description
int A return value from the list FINS_RETVAL_... indicating the result of the command


The function finslib_memory_area_write_bit() can be used to write a block of bits to a memory area in a remote PLC. The connection with the PLC should already be present before this function is called.

Data is transferred unmodified from the caller supplied buffer to the FINS data stream. Existence and filling of the dataspace is the responsibility of the calling function, but finslib_memory_area_write_bit() will return an error if a NULL pointer is provided for data storage.

The start of the memory area is provided as an ASCII string which represents the starting address in human readable format. Example formats are CIO20.0 and W100.5.

The number of bits to be written in one function call is not limited by the amount of data a PLC can send in one FINS packet because finslib_memory_area_write_bit() will automatically use multiple request at the FINS layer if the dataset is too large.

The return value is either FINS_RETVAL_SUCCESS when the function succeeded, or one of the other FINS_RETVAL_ values if an eror occurs. In the latter case depending on the error message it is not sure if none, some or all of the data has been written to the PLC and additional processing and communication with the PLC may be necessary to know or set the correct state of the memory contents of the PLC.

See Also