FP_Read
| IAStatus FP_Read | (IAHandle serverHandle, IAHandle IOPointHandle,IAByte buffer[], unsigned long bufferSize, SYSTEMTIME *timestamp); |
Purpose
This function reads the value of the I/O point specified by the I/O point handle. This is a synchronous read.
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Note The recommended method of monitoring an I/O point is to schedule an advise on an I/O point, pass NULL for the function pointer, and use a timer on the UIR to periodically read the cache on the I/O point. When you use NULL for the callbackFunction pointer, your program ignores callbackMethod. |
Parameter List
| Name | Type | Description |
|---|---|---|
| serverHandle | IAHandle | Handle to a specific server session. Create the handle with FP_Open. |
| IOPointHandle | IAHandle | Used to refer to an I/O point. You can create the handle with FP_CreateTagIOPoint. |
| buffer | IAByte[ ] | Memory that you allocate. The server copies data into this buffer. |
| bufferSize | unsigned long | Size of the buffer that you created for the read operation. The buffer size should indicate the length (in bytes) of allocated memory pointed to by the buffer pointer. |
| timestamp | SYSTEMTIME (passed by reference) | Time when the FieldPoint server read the value. The timestamp is returned in the Windows SYSTEMTIME format. |
Return Value
The LabWindows/CVI manager or the server can return the following status codes. FP_ErrorMsg converts the status codes into descriptive strings.
| LabWindows/CVI Manager-Level Error Codes | 0x8480 IA_MGR_ERROR 0x8484 IA_MGR_SERVER_NOT_LOADED 0x8487 IA_MGR_INVALID_SERVER_HND |
| FieldPoint Server-Level Standard Error Codes | 0x8000 to 0x83FF |
Refer to the error section in your server help file for more information.