The DR_ApReadBlock and DR_ApWriteBlock functions access the process I/O data area of the card. The offset and size parameters specify what portion of the buffer area to transfer, and is dependent on the field configuration. Typically, field data is always mapped to the beginning of the block (offset of 0) and is continguous up to the number of bytes defined by the field device (slave) configuration. The output process data buffer is mapped as buffer 0, while 1 will access the input process data buffer.

No control functions are currently accessible by the user.

The DR_ApReadStatus function accesses the status blocks of the card. Only buffer 1 is valid for 5136-DNP cards, which provides status information about the CANbus as well as client-server and field device status.

The status of the SST 5136-DNP Card is read from buffer 1 with a length of 80 bytes, using the function DR_ApReadStatus, as follows in this example:

DR_ApReadStatus (card, 1, 0, 80, &status, &error)

The offset parameter (0) is ignored. The size parameter can be less than the maximum size (80) if only a portion of the status structure is required. Status is a structure of type dr5136dn_ApState_t (see the file dvn_api.h) and is defined as follows:

typedef struct
{
    unsigned short CanStatus;       /* see Ap_DNS_eCAN_STATUS_CODE below */
    unsigned short CanTx;           /* CAN transmit counter              */
    unsigned short CanAck;          /* CAN ACK error counter             */
    unsigned short CanRx;           /* CAN receive counter               */
    unsigned short CanErr;          /* CAN error counter                 */
    unsigned short CanLost;         /* CAN messages lost counter         */
    unsigned short CanOverrun;      /* Receive queue overrun counter     */

    unsigned char  ClientStatus;    /* 0 Idle 1 Active                   */
    unsigned char  ServerStatus;    /* 0 Idle 1 Active                   */
    unsigned char  DeviceStatus[64];/* see Ap_DNS_eDEV_STATUS_CODE below */
}
dr5136dn_ApState_t; /* SST 5136-DN DeviceNet */

where: