DataField Attributes

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It is important to note that DataField properties are not automatically updated in the Driver. This is different behaviour to ConfigField properties.

C# .NET Example

A DataField and ConfigField have been added to a new Scanner object:

[Table("MyScanner", "MyScanner")]public class MyScanner : Scanner{    [Label("Meter Number", 1, 1)]    [ConfigField("Meter Number", "The meter number on the device", 1, 2, OPC_METER_NUMBER)]    public Byte MeterNumber;    [DataField("Last Daily Record", "The index of the last daily record that was retrieved from the meter", PemexModule.OPC_METER_DATA_LAST_DAILY_RECORD)]    public UInt16 LastDailyRecord = 0;}

In the driver, both the ConfigField and DataField can be accessed using the DBScanner property, like this:

UInt16 Val1 = DBScanner.LastDailyRecord;Byte Val2 = DBScanner.MeterNumber;

Whilst this works with ConfigField properties, such as MeterNumber, the value of DBScanner.LastDailyRecord will always be zero.

The Solution

The only way to access the LastDailyRecord member is to use the SendReceiveObject in OnDefine (or similar), like this:

Object reply = null;App.SendReceiveObject(DBScanner.Id, ACTION_GET_HISTORIC_RECORDS, null, ref reply);UInt16 Val1 = (UInt16) reply;

It should be pointed out that the ACTION_GET_HISTORIC_RECORDS action will need to be handled in the function OnReceive in the MyScanner object, like this:

public override void OnReceive(uint Type, object Data, ref object Reply){    switch (Type)    {        case ACTION_GET_HISTORIC_RECORDS:            Reply = LastHourlyRecord;            break;        default:            base.OnReceive(Type, Data, Reply);            break;    }}

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