Hello everyone, I am currently trying to write some C# code which sends commands to anywhere from 1 to 5 GPIB 488.2's through GPIB-USB-HS adapters. I have my code working for the most part but am running into trouble when sending commands to more than one controller. Below is my method for a calibration cycle on my company's instrument, most of which can be ignored. It simply takes in settings from the GUI and uses the GPIB to send motor commands to a microcontroller. Everything works fine except when I am controlling more than one, it constantly throws the exception: 'System.InvalidOperationException' in NationalInstruments.NI4882.dll due to the inner exception "EndWrite was called before BeginWrite." The problem stems from sending an EndWrite to the first device after sending the first BeginWrite. This throws a flag on the other devices which haven't received their BeginWrite commands (it doesn't happen when I am controlling just one GPIB with the same code) What is the best way to control multiple GPIBs to avoid this error? I am using the NationalInstruments.NI4882.dll in VisualStudio2015 (I implemented the work around to be able to use Measurement Studio 2015 in Visual Studio 2015). I saw something about a function called TriggerList to command multiple GPIB's but have no idea what .dll it is part of. I also am not sure which .dll contains the full function list for the GPIB's such as SENDIFC, ibwait, ibwrt, ect. All I have access to is the board and device class commands. I tried adding other .dll's to my project such as the gpib-32.dll, the visa32.dll, and the ni4882.dll but receive an error stating that they are not valid COM components. To sum up the problems I need help with: What is the best way / function to command multiple GPIB's via C# How do I access the complete GPIB function list as illustrated in this manual: NI-488.2 Function Reference Manual For Windows How do I add the rest of the .dll's such as visa32.dll to my project? (I found a post on the forums describing several various steps to try but was unable to get it working, such as using tlbimp.exe to generate a working .dll) I would greatly appreciate any help with these issues. I have been stuck for quite some time now. My program does run but occasionally gets tripped up by the exceptions and thus is not suitable for production yet. private void Run_Click(object sender, EventArgs e) { int nc = Int32.Parse(textBox9.Text); //Read in number of cycles long y; y = Convert.ToInt64(Convert.ToDouble(textBox8.Text)); //Read in Dwell Time cycleTime = (int)y; List<string> steps = new List<string>(); // Create list of attenuation steps steps.Add(textBox1.Text); steps.Add(textBox2.Text); steps.Add(textBox3.Text); steps.Add(textBox4.Text); steps.Add(textBox5.Text); steps.Add(textBox6.Text); steps.Add(textBox7.Text); _worker = new BackgroundWorker(); _worker.WorkerSupportsCancellation = true; xxx = 1; int[] cycles = new int[nc]; cycles = cycles.Select(i => 5).ToArray(); if (nc % 1 == 0) { if (cycleTime > 1.5) { _worker.DoWork += new DoWorkEventHandler((state, args) => { do { if (_worker.CancellationPending) break; foreach (int element in cycles) { Console.WriteLine(xxx); xxx++; for (int i = 0; i < 7; i++) { if (_worker.CancellationPending) break; try { if (checkBox1.Checked) { //Device 1: device.BeginWrite( ReplaceCommonEscapeSequences(steps[i]), new AsyncCallback(OnWriteComplete), null); } if (checkBox2.Checked) { //Device 2: device2.BeginWrite( ReplaceCommonEscapeSequences(steps[i]), new AsyncCallback(OnWriteComplete), null); } if (checkBox3.Checked) { //Device 3: device3.BeginWrite( ReplaceCommonEscapeSequences(steps[i]), new AsyncCallback(OnWriteComplete), null); } if (checkBox4.Checked) { //Device 4: device4.BeginWrite( ReplaceCommonEscapeSequences(steps[i]), new AsyncCallback(OnWriteComplete), null); } if (checkBox5.Checked) { //Device 5: device5.BeginWrite( ReplaceCommonEscapeSequences(steps[i]), new AsyncCallback(OnWriteComplete), null); } if (xxx > nc) { stop = false; } dwellPause = new PauseClass(); dwellPause.Pause(cycleTime * 1000); } catch (Exception ex) { ex.ToString(); MessageBox.Show(ex.Message); } } } } while (stop); }); _worker.RunWorkerAsync(); Run.Enabled = false; Stop.Enabled = true; } else { stringReadTextBox.Text = "Error: Dwell Time Too Short!"; } } else { stringReadTextBox.Text = "Error: Number of Cycles Must Be A Whole Number!"; } stringReadTextBox.Text = "Cycling For Calibration Is Complete!"; }

Clearing board ID registry with Tools in NI Visa Max but would appreciate a method of clearing the registry programmatticaly in C#

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