LibFINS API Reference – finslib_multiple_memory_area_read()

finslib_multiple_memory_area_read( sys, item, num_item );

Parameters

Parameter Type Description
sys struct fins_sys_tp * A pointer to a structure with the FINS context
item struct fins_multidata_tp * Pointer to an array of structures where each element contains the information and storage place for one item to be retrieved
num_item size_t The number of items to return

Return Value

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

Description

The function finslib_multiple_memory_area_read() is the most versatile of all memory read functions. It takes an array of elements as a parameter where each element contains information about one memory item to be read. In one function call information from multiple memory areas can be read and also value types like BCD and signed integer and value size like bit, 16 or 32 bit words may be mixed. The connection with the PLC should already be present before this function is called.

Ensuring that the array length matches the number of elements parameter in the function call is the responsibility of the calling function but finslib_multiple_memory_area_read() will return an error if a NULL pointer is provided for data storage.

For each element in the item array, the fields address and type must be filled by the calling function. The function finslib_muliple_memory_area_read() will then fill one or two of the other fields depending on the type of the requested element.

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

The type of each element is one of the FINS_DATA_TYPE... constants.

The requested number of elements is not limited by the amount of data a PLC can send in one FINS packet because finslib_multiple_memory_area_read() will automatically use multiple requests at the FINS layer if the dataset will be 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 the data in the return buffer is unreliable and should not be used.

See Also