Octet string data

The interface is capable of requesting Octet String Static and Event data as described below.

• Object 110, Variation 1-255, Octet String Static. The variation used with an Octet String is the length of the string. A response may contain a variation smaller than requested if the available string length is shorter than what was requested. Octet String objects are not included in class 0 polls.

• Object 111, Variation 1-255, Octet String Event. The variation used with an Octet String is the length of the string. A response may contain a variation smaller than requested if the available string length is shorter than what was requested.

It is recommended to use a variation of 255 when creating PI points to read an Octet String in order to read the maximum size of an Octet String. If the size of the Octet String received from the RTU is less than 255, the length of the Octet String stored in the PI Data Archive will reflect the smaller size.

PI points for Octet Strings may be defined as PI string or blob types. PI blob types will always contain the entire Octet String received from the RTU. PI string types will contain the entire Octet String received from the RTU as long as the Octet String does not contain a null(0x00) character. If the Octet String contains one or more null(0x00) characters, the PI string will truncate the Octet String at the first null character found in the Octet String.

Example:

Received Octet String = {0x01,0x02,0x03,0x04,0x00,0x06,0x07,0x00,0x09}. Length = 9

Value in PI blob = {0x01,0x02,0x03,0x04,0x00,0x06,0x07,0x00,0x09}. Length = 9

Value PI string = {0x01,0x02,0x03,0x04}. Length = 4