Days of research and programming have led me to try all variants of inpout32.dll and inpoutx64.dll: binaries, source code, 32-bit, 64-bit, address wrappers. None work: no change is seen to the output bits of the port.
However, I know it is possible, because using another commercially available program that does parallel port output, I can detect a trigger (state change) on all eight output bits (D0-D7) by passing a value between 0 and 255, exactly what I want to do in my own application.
I have followed all the advice from at least these pages:
- Write to parallel port in Windows 7
- C# LPT inpout32.dll
- C# - Read Parallel Port State (Simple Push Switch)
- Write to a parallel port on windows 7
- Parallel port with C#
I am using Windows 7, 64-bit; and my SIIG Cyberpro port is mapped as LPT3 at address 0xCCD8, with four status bits at address 0xCCD4. I have another ECP printer port mapped as LPT1 at 0x0378, but that does not work either.
I know better than to try direct _inp(), _outp() calls on Win7.
Can anyone help?
If I need to download and modify the driver code, I can do that if I have to, but I think it should not be that difficult.
My final version of code uses 32-bit compilation, interfacing to inpout32.dll:
using System; using System.Runtime.InteropServices; namespace ParallelPort { public class PortAccess { //inpout.dll [DllImport("inpout32.dll")] private static extern void Out32(ushort PortAddress, short Data); [DllImport("inpout32.dll")] private static extern short Inp32(ushort PortAddress); private ushort _PortAddress = 0; public ushort PortAddress { get { return _PortAddress; } } public PortAccess(ushort portAddress) { _PortAddress = portAddress; short result = 0; try { result = Inp32(portAddress); } catch (DllNotFoundException e) { throw new ArgumentException("Unable to find InpOut32.dll"); } catch (BadImageFormatException) { result = 0; } if (0 == result) throw new ArgumentException("Unable to open parallel port driver"); } //Public Methods public void Write(ushort Data) { Out32(_PortAddress, (short)Data); } public byte Read() { return (byte)Inp32(_PortAddress); } } } 1 Answer
FYI:
When I added
[DllImport("inpout32.dll")] private static extern void DlPortWritePortUshort(ushort PortAddress, ushort Data); and called that function rather than Out32(ushort addr, ushort value) the code worked.
I don't know why the exact interface matters, but it does; and perhaps that is indeed because of sign extension on the 16-bit port address, as suggested [somewhere TBD].
