Rockwell-automation 1747-PCINT API Software for 1746 I/O Manual de usuario descargar pdf (Pagina 146)

6–92 Library of Routines OC_WriteSRAM

Publication 1747-6.5.3 June 1998

OC_WriteSRAM OC_WriteSRAM wires data to the battery-backed user memory

Syntax:

int OC_WriteSRAM(HANDLE Handle, BYTE*bufptr, DWORD offset, DWORD length);

Description:

The battery-backed memory may be used to store important data that needs to be preserved in the event of

a power failure. The size of the available memory in bytes may be obtained using OC_GetDeviceInfo.

Important: It is recommended that the integrity of data stored in the user memory

be verified by some means. The OC_CalculateCRC function may be

used to generate a 16-bit CRC that may be used for this purpose.

handle must be a valid handle returned from OC_OpenScanner. bufptr points to the data to be written.

offset specifies the offset within the memroy to begin writing. length specifiies the number of bytes

to be written.

offset

length

points past the end of the memory, no bytes will be written and ERR_OCPRAM

will be returned.

Return Value:

Considerations:

Supported in the Windows NT API library only.

Example:

Byte buf[100]; /*buffer of important data*/

Word crc;

HANDLE handle;

/* Save 100 bytes of data to offset 0 in SRAM */

OC_WriteSRAM(handle, buf, 0, 100);

/* Calculate CRC */

OC_CalculateCRC(buf, 100, &crc);

/* Write data CRC to offset 100 in SRAM */

OC_WriteSRAM(handle, &crc, 100, 2);

Name: Description:

SUCCESS data was written successfully

ERR_OCACCESS handle does not have access to scanner

ERR_OCPARAM offset+length points past the end of the memory

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Rockwell-automation 1747-PCINT API Software for 1746 I/O Manual de usuario Pagina 146