public override async Task <VTQ[]> ReadDataItems(string group, IList <ReadRequest> items, Duration?timeout)
{
int N = items.Count;
if (!await TryConnect() || networkStream == null || config == null)
{
return(GetBadVTQs(items));
}
VTQ[] vtqs = new VTQ[N];
byte[] writeBuffer = new byte[7 + 5]; // 7: Header, 5: PDU
for (int i = 0; i < N; ++i)
{
ReadRequest request = items[i];
if (mapId2Info.ContainsKey(request.ID))
{
ItemInfo item = mapId2Info[request.ID];
ModbusAddress address = item.Address;
WriteUShort(writeBuffer, 0, (ushort)i); // Transaction-ID
WriteUShort(writeBuffer, 2, 0); // Protocol-ID
WriteUShort(writeBuffer, 4, 6); // Length
writeBuffer[6] = GetModbusHeaderAddress(config, item.Item);
writeBuffer[7] = GetModbusFunctionCode(config, item.Item);
WriteUShort(writeBuffer, 8, (ushort)(address.Start - 1));
WriteUShort(writeBuffer, 10, address.Count);
try {
await networkStream.WriteAsync(writeBuffer);
ushort[] words = await ReadResponse(networkStream, address.Count);
vtqs[i] = ParseModbusResponse(item.Item, words, Timestamp.Now);
}
catch (Exception exp) {
Exception e = exp.GetBaseException() ?? exp;
LogWarn("ReadExcept", $"Failed to read item {item.Item.Name}: {e.Message}");
vtqs[i] = VTQ.Make(request.LastValue.V, Timestamp.Now, Quality.Bad);
CloseConnection();
}
}
else
{
vtqs[i] = VTQ.Make(request.LastValue.V, Timestamp.Now, Quality.Bad);
}
}
return(vtqs);
}
protected virtual ModbusAddress GetModbusAddress(DataItem item)
{
bool is8Bit = item.Type == DataType.Byte || item.Type == DataType.SByte;
int dimension = Math.Max(1, item.Dimension);
string address = item.Address;
ushort count = is8Bit ?
(ushort)(dimension / 2 + dimension % 2) :
(ushort)(RegisterPerType(item.Type) * dimension);
if (is8Bit && (address.EndsWith('L') || address.EndsWith('H')))
{
address = address.Substring(0, address.Length - 1);
}
ushort add = ushort.Parse(address);
if (add == 0)
{
throw new Exception("Modbus register may not be zero. First register starts with 1.");
}
return(ModbusAddress.Make(add, count));
}
public ItemInfo(DataItem item, ModbusAddress address)
{
Item = item;
Address = address;
}
