private async Task PerformWriteAsync(ICollection <IPlcItem> plcItems, CancellationToken cancellationToken)
{
const PlcItemUsageType usageType = PlcItemUsageType.Write;
var underlyingPlc = AgLinkPlc.VerifyConnectivity(this, plcItems, usageType);
// Create the mapping.
var(mapping, allAgLinkItems) = AgLinkPlc.CreateMappingAndAgLinkItems(plcItems, usageType);
// Write to the plc.
var writeResult = await Task.Run(() => underlyingPlc.WriteMixEx(allAgLinkItems, allAgLinkItems.Length), cancellationToken);
// Verify the total result.
//! Ignore the total result and inspect the result of each item individually.
var result = AgLinkPlc.ConvertToAgLinkResult(writeResult);
//if (result != AgLinkResult.Success)
//{
// var errorMessage = AgLinkPlc.ErrorMapping.GetErrorMessageForCode(writeResult);
// var items = plcItems.Select(item => (item, "General writing error.")).ToArray();
// throw new WritePlcException(new IPlcItem[0], items, $"Could not write any items to {this:LOG}. AGLink returned error code '{result}' ({errorMessage}).");
//}
// Verify the result of all items.
var(validItems, failedItems) = AgLinkPlc.VerifyPlcItemResults(mapping, allAgLinkItems, false);
if (failedItems.Any())
{
throw new WritePlcException(validItems, failedItems, $"Some of the items couldn't be written. See the '{nameof(ReadOrWritePlcException.FailedItems)}' property for further information.");
}
}
private async Task PerformReadAsync(ICollection <IPlcItem> plcItems, CancellationToken cancellationToken)
{
const PlcItemUsageType usageType = PlcItemUsageType.Read;
var underlyingPlc = AgLinkPlc.VerifyConnectivity(this, plcItems, usageType);
// Create the mapping.
var(mapping, allAgLinkItems) = AgLinkPlc.CreateMappingAndAgLinkItems(plcItems, usageType);
// Read from the plc.
//! The return value may be zero even if some or all of the items failed. To get the real result the 'Result' property of the AGLink item (AGL4.DATA_RW40.Result) must be checked.
var readResult = await Task.Run(() => underlyingPlc.ReadMixEx(allAgLinkItems, allAgLinkItems.Length), cancellationToken);
// Verify the total result.
//! Ignore the total result and inspect the result of each item individually.
var result = AgLinkPlc.ConvertToAgLinkResult(readResult);
//if (result != AgLinkResult.Success)
//{
// var errorMessage = AgLinkPlc.ErrorMapping.GetErrorMessageForCode(readResult);
// var items = plcItems.Select(item => (item, "General reading error.")).ToArray();
// throw new ReadPlcException(new IPlcItem[0], items, $"Could not read any items from {this:LOG}. AGLink returned error code '{result}' ({errorMessage}).");
//}
// Verify the result of all items and transfer the value.
var(validItems, failedItems) = AgLinkPlc.VerifyPlcItemResults(mapping, allAgLinkItems, true);
if (failedItems.Any())
{
throw new ReadPlcException(validItems, failedItems, $"Some of the items couldn't be read. See the '{nameof(ReadOrWritePlcException.FailedItems)}' property for further information.");
}
}
/// <summary> /// Asynchronously reads or writes the <paramref name="plcItems"/> to / from the plc. /// </summary> /// <param name="plcItems"> The <see cref="IPlcItem"/>s to write. </param> /// <param name="usageType"> The <see cref="PlcItemUsageType"/> defining whether a read or a write operation is performed. </param> /// <param name="cancellationToken"> A <see cref="CancellationToken"/> for cancelling the operation. </param> protected internal abstract Task PerformReadWriteAsync(ICollection <IPlcItem> plcItems, PlcItemUsageType usageType, CancellationToken cancellationToken);
private async Task <bool> ExecuteReadWriteAsync(ICollection <IPlcItem> plcItems, PlcItemUsageType usageType, CancellationToken cancellationToken)
{
// Allow only items that have a length greater than zero. This is mostly needed for dynamic items.
plcItems = plcItems.Where(item => item.Value.Length > 0).ToList();
if (!plcItems.Any())
{
return(true);
}
var cancellationTokenSource = this.BuildLinkedTokenSource(cancellationToken);
cancellationToken = cancellationTokenSource.Token;
try
{
while (true)
{
try
{
cancellationToken.ThrowIfCancellationRequested();
lock (_connectionStateChangeLock)
{
// If no active connection is available, then throw an exception.
/*!
* This means, that reading/writing items while the plc is not connected, will result in the calling function to indefinitely wait,
* because no reconnect will be made when the connection was deliberately not established.
*/
if (this.ConnectionState == PlcConnectionState.Disconnected)
{
var itemDescriptions = Plc.GetPlcItemDescription(plcItems);
throw new NotConnectedPlcException($"Cannot {usageType.ToString().ToLower()} the plc items ({itemDescriptions}) because {this:LOG} is not connected. All items will be put on hold.");
}
}
await Task.Run(() => this.PerformReadWriteAsync(plcItems, usageType, cancellationToken), cancellationToken);
break;
}
// This handles task cancellation.
catch (OperationCanceledException)
{
if (_disposeToken.IsCancellationRequested)
{
if (usageType == PlcItemUsageType.Read)
{
throw new DisposedReadPlcException(plcItems);
}
else
{
throw new DisposedWritePlcException(plcItems);
}
}
return(false);
}
// Handle not connected exceptions by trying to re-connect and halting the items until a connection was established.
catch (NotConnectedPlcException ex)
{
this.Logger.Error(ex.Message);
// Create a cancellation token source for this handle callback that is linked to the external one.
var sleepCancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
_waitQueue.Enqueue(sleepCancellationTokenSource);
var sleepCancellationToken = sleepCancellationTokenSource.Token;
// Check if a reconnection could be useful.
lock (_connectionStateChangeLock)
{
// Don't reconnect if the connection is disconnected to begin with.
if (this.ConnectionState != PlcConnectionState.Disconnected)
{
this.OnInterrupted(executeReconnect: true);
}
}
// Indefinitely wait until the task gets canceled.
try
{
await Task.Delay(Timeout.Infinite, sleepCancellationToken);
}
catch (OperationCanceledException)
{
// Throw special dispose exception if the dispose token was canceled.
if (_disposeToken.IsCancellationRequested)
{
if (usageType == PlcItemUsageType.Read)
{
throw new DisposedReadPlcException(plcItems);
}
else
{
throw new DisposedWritePlcException(plcItems);
}
}
// Stop execution if the original (external) token was canceled.
else if (cancellationToken.IsCancellationRequested)
{
return(false);
}
// In all other cases just keep going.
else
{
/* ignore */
}
}
this.Logger.Info($"The previously suspended plc items of {this:LOG} will now be handled again.");
}
// Throw on read or write exceptions.
catch (ReadOrWritePlcException)
{
throw;
}
}
return(true);
}
finally
{
cancellationTokenSource.Dispose();
cancellationTokenSource = null;
#if DEBUG
this.LinkedTokenWasCanceled();
#endif
}
}
/// <inheritdoc />
protected override async Task PerformReadWriteAsync(ICollection <IPlcItem> plcItems, PlcItemUsageType usageType, CancellationToken cancellationToken)
{
try
{
if (usageType == PlcItemUsageType.Read)
{
await this.PerformReadAsync(plcItems, cancellationToken);
}
else
{
await this.PerformWriteAsync(plcItems, cancellationToken);
}
}
catch (NullReferenceException)
{
throw;
}
}
private static IEnumerable <AGL4.DATA_RW40> CreateAgLinkItems(IPlcItem plcItem, PlcItemUsageType usageType)
{
var agLinkItem = new AGL4.DATA_RW40
{
Offset = plcItem.Position
};
switch (plcItem.Type)
{
case PlcItemType.Input:
agLinkItem.DBNr = 0;
agLinkItem.OpArea = AGL4.AREA_IN;
break;
case PlcItemType.Output:
agLinkItem.DBNr = 0;
agLinkItem.OpArea = AGL4.AREA_OUT;
break;
case PlcItemType.Flags:
agLinkItem.DBNr = 0;
agLinkItem.OpArea = AGL4.AREA_FLAG;
break;
default:
case PlcItemType.Data:
agLinkItem.DBNr = plcItem.DataBlock;
agLinkItem.OpArea = AGL4.AREA_DATA;
break;
}
if (plcItem.Value.HandlesFullBytes || (usageType == PlcItemUsageType.Read && plcItem.Value.Length > 1))
{
agLinkItem.OpType = AGL4.TYP_BYTE;
agLinkItem.BitNr = 0;
agLinkItem.OpAnz = (ushort)DataHelper.GetByteAmountForBits(plcItem.Value.Length);
if (usageType == PlcItemUsageType.Write)
{
agLinkItem.B = plcItem.Value;
}
else
{
agLinkItem.B = new byte[agLinkItem.OpAnz];
}
yield return(agLinkItem);
}
else
{
agLinkItem.OpType = AGL4.TYP_BIT;
agLinkItem.OpAnz = 1;
for (byte bitPosition = 0; bitPosition < plcItem.Value.Length; bitPosition++)
{
var bitAgLinkItem = agLinkItem; // Value type will be copied on assignment.
bitAgLinkItem.BitNr = (ushort)(bitPosition + plcItem.BitPosition);
if (usageType == PlcItemUsageType.Write)
{
// Get the relevant bit of this item and set the AGLink byte accordingly.
bitAgLinkItem.B = new byte[] { plcItem.Value[bitPosition] ? (byte)1 : (byte)0 };
}
else
{
bitAgLinkItem.B = new byte[1];
}
yield return(bitAgLinkItem);
}
}
}
private static (ICollection <ReadPlcItemWrapper> Mapping, AGL4.DATA_RW40[] AllAgLinkItems) CreateMappingAndAgLinkItems(ICollection <IPlcItem> plcItems, PlcItemUsageType usageType)
{
var mapping = plcItems
.Select(plcItem => new ReadPlcItemWrapper(plcItem))
.ToArray()
;
// Create all needed AGLink items.
//! Directly storing the AGLink items in the ReadPlcItemWrapper instance won't work, as AGL4.DATA_RW40 is a struct that would consequently be copied on assignment.
//! Therefore the ReadPlcItemWrapper only contains the start position and the amount of items in the returned AGLink items array.
var previousAmount = 0;
var allAgLinkItems = mapping
.SelectMany
(
readPlcItemWrapper =>
{
var agLinkItems = AgLinkPlc.CreateAgLinkItems(readPlcItemWrapper.PlcItem, usageType).ToArray();
readPlcItemWrapper.Start = (previousAmount += agLinkItems.Length) - 1;
readPlcItemWrapper.Amount = agLinkItems.Length;
return(agLinkItems);
}
)
.ToArray()
;
return(mapping, allAgLinkItems);
}
private static IAGLink4 VerifyConnectivity(AgLinkPlc plc, ICollection <IPlcItem> plcItems, PlcItemUsageType usageType)
{
var underlyingPlc = plc.UnderlyingPlc;
if (underlyingPlc is null)
{
var itemDescriptions = Plc.GetPlcItemDescription(plcItems);
throw new NotConnectedPlcException($"Cannot {usageType.ToString().ToLower()} the plc items ({itemDescriptions}) because {plc:LOG} is not connected. All items will be put on hold.");
}
return(underlyingPlc);
}
