Checksum

A checksum is available in AVEVA Recipe Management so you can verify the downloads to your IO references are successful. The use of the checksum is optional. If you want to use the checksum, you must enter an IO reference for the checksum target.

All the other fields are optional.

The checksum verification process is as follows:

1. AVEVA Recipe Management writes the parameters and ChecksumTarget to the control system.

2. AVEVA Recipe Management sets the ControlStart to true.

3. The control system determines what state to go to next.

Modify the Checksum Algorithm

A default checksum algorithm is provided for you:

The default algorithm:

• Calculates a 31-bit integer value (32-bit signed integer value with sign bit dropped)

• Uses only parameter targets of the following types: Integer and Double

• Converts Doubles to Integers first by multiplying them by 1000, and truncating the remaining decimal portion of the number

You can modify this algorithm in the RecMngrPlusDB database in SQL server. If you do plan to modify the checksum algorithm, we recommend you back up the default version first. Refer to the stored procedure USP_CalculateWriteVerificationValue for the exact details of the checksum algorithm.