I created a C# DLL using modbus-protocoll to read an analog-value from a module.
In a second c#-project i use the dll and create an object with "new ET18Z_A". Everything works fine as long as i only use one module. When i create a second object (ET18Z_B) then the first is not working any more.
It seems as if the second "new" overwrite the first session.
Here the code that i use to read one value. If the second "new" is skipped and it is running good and function ReadInputRegister reads the correct value. If i make the three lines active and the second "new" is also active then the function ReadInputRegister does not read the correct value. There is also no error but the result is wrong.
ET7018Z.ET7018Z ET18Z_A = new ET7018Z.ET7018Z();
string IP_ET7018Z = "192.168.100.110";
Res = ET18Z_A.Initialize(IP_ET7018Z, out Message);
//The next three lines open connection to a second module with different IP
//ET7018Z.ET7018Z ET18Z_B = new ET7018Z.ET7018Z();
//IP_ET7018Z = "192.168.100.210";
//Res = ET18Z_B.Initialize(IP_ET7018Z, out Message);
int AI_7018Z = 0
Res = ET18Z_A.ReadInputRegister(AI_7018Z, out Value, out Message);
The Initialize function looks like this:
public class ET7018Z
{
static ModbusIpMaster master;
public int Initialize(string IP, out string Message)
{
Message = "No Error";
try
{
string ipAddress = IP;
int tcpPort = 502;
TcpClient tcpClient = new TcpClient();
tcpClient.BeginConnect(ipAddress, tcpPort, null, null);
master = ModbusIpMaster.CreateIp(tcpClient);
Thread.Sleep(100);
string message = "";
int Res = 0;
Res = SetEngineeringFormat(CState.ON, out message);
return 0;
}
}
}
What is wrong here?
Solution is to remove the "static" in this line:
static ModbusIpMaster master;
Related
How can I ban a variable from a list without removing it from that list by adding the variable to a list of "banned" variable?
I wish to be able to type in a string. That string is compared to the file names in a folder. If there is a match, the file is read. If I type this same string again, the file should not be read again. There for I want to have a list of "banned" string that is checked whilst typing to avoid the file to be read again.
I have tried a few ways but not getting there. Below is an example of my last attempt.
What would be the best way?
public class test
{
string scl= "test3";
List <string> lsf,lso;
void Start ()
{
lsf=//file names
new List<string>();
lso=//files open
new List<string>();
lsf.Add("test0");
lsf.Add("test1");
lsf.Add("test2");
lsf.Add("test3");
lsf.Add("test4");
lso.Add("idhtk49fngo");//random string
}
void Update ()
{
if
(
Input.GetKeyDown("a")
)
{
for
(
int i=0;
i<lsf.Count;
i++
)
{
if(lsf[i]==scl)
{
Debug.Log
(i+" is read");
for
(
int j=0;
j<lso.Count;
j++
)
{
//how can i avoid reading
//lsf[3] here the second time
//"a" is pressed (by having "test3"
//added to a "ban" list (lso) )
if(scl!=lso[j])
{
lso.Add(lsf[i]);
}
}
}
}
}
}
Michael’s answer is the way to go here but it can be improved using the more appropriate collection available to keep track of opened files; if you want uniqueness use a set, not a list:
HashSet<string> openedFiles = new HashSet<string>();
public static bool TryFirstRead(
string path,
out string result)
{
if (openedFiles.Add(path))
{
result = File.ReadAllText(path);
return true;
}
result = null;
return false;
}
Also, I’d avoid throwing vexing exceptions. Give the consumer a friendly way to know if the file was read or not, don’t make them end up having to use exceptions as a flow control mechanism.
I didn't understand although if you want to replace a value from another list.
You can use the list index to create a new list with the values which you removed.
String list1 = {"hi", "hello", "World"};
String list2 = {"bye", "goodbye", "World"};
List1[1] = list2[1];
I would suggest such way:
public static List<string> openedFiles = new List<string>();
public static string ReadFileAndAddToOpenedList(string path)
{
if (openedFiles.Contains(path))
throw new Exception("File already opened");
// Instead of throwing exception you could for example just log this or do something else, like:
// Consolle.WriteLine("File already opened");
else
{
openedFiles.Add(path);
return File.ReadAllText(path);
}
}
The idea is - on every file read, add file to list, so you can check every time you try read file, if it was already read (or opened). If it is, throw exception (or do something else). Else read a file.
You could instead of making it a string list use your own class
public class MyFile
{
public string Name;
public bool isOpen;
public MyFile(string name)
{
Name = name;
isOpen = false;
}
}
List<MyFile> lsf = new List<MyFile>()
{
new MyFile("test0"),
new MyFile("test1"),
new MyFile("test2"),
new MyFile("test3"),
new MyFile("test4")
};
Than when you read the file set isOpen to true
MyFile[someIndex].isOpen = true;
and later you can check this
// E.g. skip in a loop
if(MyFile[someIndex]) continue;
You could than also use Linq in order to get a list of only unread files:
var unreadFiles = lsf.Select(f => f.Name).Where(file => !file.isOpen);
I am really new to coding, never studied it or something similar, just learning it myself, never done it before, but I am trying to create my first real application right new.
However, I have some problems for 2 days which I just can't figure out, so I hope you can help me out.
Alright, so before the youtubedlCurrentWorker_Process() is created, I did define 'public string CurrentYouTubeDLVersion'.
How ever, when a button in my application executes the youtubedlCompareVersion_Process(), the CurrentYouTubeDLVersion string is empty, when it comes at the compare point.
Below is just a little part of my code.
Why is the string CurrentYouTubeDLVersion empty in the CompareVersion while the GetCurrentVersion ran before it?
Even if I double click "CurrentYouTubeDLVersion" in Visual Studio, it won't show a link to the one in the GetCurrentVersion_Process.
namespace MediaDownloader
{
public partial class updates : UserControl
{
public string LatestYoutubeDLVersion;
public string CurrentYouTubeDLVersion;
public void youtubedlGetCurrentVersion_Process()
{
if (File.Exists(YouTubeDLPath))
{
//Here I get the current version of youtube-dl.exe, to get the version number, we have to run youtube-dl.exe --version
Process youtubedl = new Process();
youtubedl.StartInfo.CreateNoWindow = true;
youtubedl.StartInfo.UseShellExecute = false;
youtubedl.StartInfo.RedirectStandardOutput = true;
youtubedl.StartInfo.RedirectStandardError = true;
youtubedl.StartInfo.FileName = YouTubeDLPath;
youtubedl.StartInfo.Arguments = " --version";
youtubedl.Start();
string CurrentYouTubeDLVersion = youtubedl.StandardOutput.ReadToEnd();
this.Dispatcher.Invoke((Action)(() =>
{
CurrentYouTubeDLVersionText.Text = "Current youtube-dl.exe version: " + CurrentYouTubeDLVersion;
YouTubeDLVersionStatusText.Text = null;
UpdateYouTubeDL.IsEnabled = false;
}));
}
public void youtubedlCompareVersion_Process()
{
youtubedlGetCurrentVersion_Process();
string LatestYoutubeDLVersion = WebClient.DownloadString("https://yt-dl.org/latest/version");
MessageBox.Show("Latest:" + LatestYoutubeDLVersion + "Current " + CurrentYouTubeDLVersion);
int YouTubeDLUptodate = CurrentYouTubeDLVersion.CompareTo(LatestYoutubeDLVersion);
if (YouTubeDLUptodate < 1)
{
YouTubeDLVersionStatusText.Text = "Your youtube-dl.exe is out of date, please click the button below to update.";
UpdateYouTubeDL.IsEnabled = true;
}
else
{
YouTubeDLVersionStatusText.Text = "youtube-dl.exe is up to date!";
UpdateYouTubeDL.IsEnabled = false;
}
}
}
Inside the youtubedlGetCurrentVersion_Process method, you're creating a new CurrentYouTubeDLVersion string, and it's completely separate from the public CurrentYouTubeDLVersion you added to the top of the class.
string CurrentYouTubeDLVersion = youtubedl.StandardOutput.ReadToEnd();
Assign to the class-level variable you made, instead of creating a new string:
CurrentYouTubeDLVersion = youtubedl.StandardOutput.ReadToEnd();
Then the value will be available to you in youtubedlCompareVersion_Process.
Take out the 'string' in front of CurrentYouTubeDLVersion and it should work
public youtubedlGetCurrentVersion_Process()
{
/* removed code to make easier to read */
//string CurrentYouTubeDLVersion = youtubedl.StandardOutput.ReadToEnd();
CurrentYouTubeDLVersion = youtubedl.StandardOutput.ReadToEnd();
/* removed code to make easier to read */
}
I am using the Xi interface to retrieve data from an OPC .NET server. The issue that I am having though is that the server seems to be incorrectly identifying a parameter as not being historized.
Even though all the information from DeltaV indicates that the corresponding parameter for the ObjectAttributes object returned from the server should indicate that it is collecting history, the IsCollectingHistory property actually indicates that it is false.
History collection is enabled:
The parameter in question is in the history collection:
I won't include the screenshot but I can also open the historical trend for that parameter. But as you can see below, when I inspect the retrieved object while debugging, it says that it is not being historized.
Here is some of the code that I am using:
FindCriteria criteria = createCriteria(path, false);
List<Parameter> parameters = new List<Parameter>();
IEnumerable<ObjectAttributes> enumerableObject;
int i = 0;
try
{
enumerableObject = iContext.FindObjects(criteria, 50);
}
catch (System.ServiceModel.FaultException)
{
//This error is thrown when no data is returned.
return null;
}
A few lines down, I then do some object initialization for my Parameter object, assigning it the properteries from the object that was received from the server. It is not shown below but I then add my Parameter object to a collection if it is being historized. It never gets added to the collection because the IsCollectingHistory property is always false.
enumerableObject = enumerableObject.Skip(1);
foreach (ObjectAttributes oa in enumerableObject)
{
Parameter _parameter = new Parameter
{
IsHistorized = oa.IsCollectingHistory,
IsLeaf = oa.IsLeaf
};
//...
Any ideas on where I am going wrong?
Edit:
After trying MotteAndBailey's answer, an error is thrown at the call to AddNewDataObjectToDataJournalList. The message associated with it is "The OPC HDA Create Browse failed".
Below is a screenshot of the error in a message box when using HDAprobe:
Some info on properties in OPC.NET -
The Xi server wraps the OPCDA and OPCHDA servers. The item properties (attributes) available on each server and the means of accessing them using Classic (DCOM) OPC vary considerably.
OPCDA
The OPCDA server provides a method for determining item properties:
IOPCItemProperties::GetItemProperties()
This call provides the client with a way to read all an item’s attribute values using the item ID (string path for the item in the Server’s address space) and propertyID. The Xi server uses this call when performing a FindObjects() call. FindObjects() returns all the properties exposed by the OPCDA server for an item.
OPCHDA
The OPCHDA server has a method for determining item properties, but it requires the item handle not the ItemID/path:
IOPCHDA_SyncRead::ReadAttribute()
As a result, the FindObjects() call for an OPCHDA server through Xi only returns the item ID property. The other attributes are set to defaults. To determine what the actual values of the other properties are a user must add the item to a list and call ReadAttribute() on the specific property they wish to see.
In summary, the OPCDA server works pretty much like you would expect and returns the object properties in a single method call; however, the OPCHDA server requires an additional step to get all the object properties.
The sample code will produce an Xi Journal list with only the on-scan history items.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xi.Client.Base.API;
using Xi.Client.Base;
using Xi.Contracts;
using Xi.Contracts.Data;
using Xi.Contracts.Constants;
using System.ServiceModel.Description;
using Xi.Client.CommonDialogs;
using System.Runtime.Serialization;
namespace ConsoleFindObjectsHDA
{
public class DotNetSupport
{
IXiEndpointDiscovery iEndpointDiscovery;
IXiContext iContext;
IXiEndpointBase readEndpoint;
ServiceEndpoint RMSvcEndpt;
//the list of items the user is trying to read
IXiDataJournalList iDataJournalList;
public void GetSomeData()
{
//get a connection to an OPC.NET server
if (Connect())
{
//we have to have a list to add a tag to and hold returned datasets
if (CreateJournalList())
{
//now use the list to add items and read their attributes - only "good" ones will be left on the list
ListAllHDAItemsOnScan();
if (iDataJournalList.Count() > 0)
{
//at this point we <should> have a DataJournalList containing only the HDA items on scan
//we can use the normal data read methods to get history for the items if we wish
// <do some history thing here>
}
else
{
Console.WriteLine("\nThere were no points on-scan in the historian");
}
Console.WriteLine("\nPress <return> to exit program");
Console.ReadLine();
}
////clean up if we have open connections/contexts
Cleanup();
}
}
//we will use FindObjects to browse all the leaves in the HDA server, then add them one-by-one to a datalist
//when we query their on-scan property and it is true we leave them on the list
//...if not, we remove them (giving us a list of the good HDA points)
void ListAllHDAItemsOnScan()
{
FindCriteria criteria = GetLeafCriteria();
IEnumerable<ObjectAttributes> enumerableObject;
try
{
//ask the server for a list of leaves...up to 50 max returned in this call
enumerableObject = iContext.FindObjects(criteria, 50);
//for each string itemID: add it to the list, read the attribute, and remove it from the list if not on-scan
foreach (ObjectAttributes oa in enumerableObject)
{
//we do not have to commit this because we have indicated the operation is NOT prep-only
Console.WriteLine("Adding OPCHDA item {0}.", oa.InstanceId.LocalId);
IXiHistoricalDataObject ixObject = iDataJournalList.AddNewDataObjectToDataJournalList(oa.InstanceId, false);
//we are getting the CURRENT (from NOW -to- NOW) item status
FilterCriterion fc1 = GetFilterCriteriaDateTime(DateTime.Now);
//tell the server what property (attribute) we want to read
List<TypeId> lstp = new List<TypeId>();
TypeId typeit = new TypeId("", "", DVServerAttributes.DELTAV_DVCH_ON_SCAN.ToString());
lstp.Add(typeit);
//read the property from the server
iDataJournalList.ReadJournalDataProperties(fc1, fc1, ixObject, lstp);
//find the current item and check it for "on-scan"
if (ixObject != null)
{
if (ixObject.PropertyValues.First().PropertyValues.UintValues.First() == 1)
{
Console.WriteLine("OPCHDA item {0} is on-scan.\n", oa.InstanceId.LocalId);
}
else
{
if (ixObject.PrepForRemove())
{
Console.WriteLine("OPCHDA item {0} is not on-scan. Removing item.\n", oa.InstanceId.LocalId);
iDataJournalList.CommitRemoveableElements();
}
}
}
}
}
catch (Exception ex)
{
Console.WriteLine("Exception in FindObjects(). The exception is:{0}\n", ex.Message);
}
}
//create a filtercriterion for a specific date time - this is an EQUAL (not > or <) comparison operator
public FilterCriterion GetFilterCriteriaDateTime(DateTime dtChosenTime)
{
//simple timestamp filter which is used by the read call
FilterCriterion filterCriterion = null;
// this is a timestamp
string filterOperand = FilterOperandNames.Timestamp;
//make the given time with UTC/Local set to local time just to be sure
DateTime dtTmp1 = DateTime.SpecifyKind(dtChosenTime, DateTimeKind.Local);
object comparisonValue = dtTmp1;
//timestamp equal to this one
uint oper = FilterOperator.Equal;
//create the filter
filterCriterion = new FilterCriterion()
{
OperandName = filterOperand,
Operator = oper,
ComparisonValue = comparisonValue,
};
return filterCriterion;
}
//create a filtercriterion for leaves (OPCHDA items)
public FilterCriterion GetLeafFilterCriterion()
{
//simple filter for leaves
FilterCriterion filterCriterion = null;
// what this criterion applies to
string filterOperand = FilterOperandNames.BranchOrLeaf;
//Must equal "LEAF" to match
uint oper = FilterOperator.Equal;
//create the filter
filterCriterion = new FilterCriterion()
{
OperandName = filterOperand,
Operator = oper,
ComparisonValue = "LEAF",
};
return filterCriterion;
}
//set up the FindCriteria search of the server
public FindCriteria GetLeafCriteria()
{
FindCriteria findCriteria = null;
findCriteria = new FindCriteria();
//our browse starts at the root - NULL means "continue browsing from where you are"
findCriteria.StartingPath = new ObjectPath("//", "HDA");
//a list of OR-ed filter criteria (we have only one)
ORedFilters orthefilters = new ORedFilters();
//the FilterCriteria list (there is only one criterion)
orthefilters.FilterCriteria = new List<FilterCriterion>();
orthefilters.FilterCriteria.Add(GetLeafFilterCriterion()); //we want leaves
//add our OR-ed filter to the filterset filters list (whew!)
findCriteria.FilterSet = new FilterSet();
findCriteria.FilterSet.Filters = new List<ORedFilters>();
findCriteria.FilterSet.Filters.Add(orthefilters);
return findCriteria;
}
//connect to the OPC.NET server and get a read endpoint
public bool Connect()
{
//set this to point to your OPC.Net server
string serverUrl = "http://localhost:58080/XiServices/ServerDiscovery";
bool bReturnVal = false;
try
{
Console.WriteLine("Getting Endpoint Discovery from server:\n{0}\n", serverUrl);
//This class is used to locate a server and obtain its list of ServiceEndpoints.
iEndpointDiscovery = new XiEndpointDiscovery(serverUrl) as IXiEndpointDiscovery;
//we have the server...now check for endpoints
//there should always be TCP endpoints for a DeltaV OPC.NET server so we do not search HTTP and Named Pipes to find one
//and we do not consider choosing the fastest option between the three (TCP/HTTP/NamedPipes). We just use the TCP/IP one.
// GetServiceEndpointsByBinding searches the list of endpoints on the XiEndpointDiscovery connection with the specified contractType and binding type.
// We use the ResourceManagement endpoint to find the the other open endpoints on the server (some might be disabled)
IEnumerable<ServiceEndpoint> resourceEndpoints = iEndpointDiscovery.GetServiceEndpointsByBinding(typeof(IResourceManagement).Name, typeof(System.ServiceModel.NetTcpBinding));
//use the first (probably only) resource endpoint for TCP/IP to open a context between client and server
if ((resourceEndpoints != null) && (resourceEndpoints.Count() > 0))
{
var serviceEndpoints = resourceEndpoints as IList<ServiceEndpoint> ?? resourceEndpoints.ToList();
//pick the first RM endpoint we found
RMSvcEndpt = ((IList<ServiceEndpoint>)serviceEndpoints).First();
//Open the Context using the RM endpoint and some other values including timeout, what we want to read (HDA), and the GUID for this context
Console.WriteLine("Opening Client Context with Initiate\n");
iContext = XiContext.Initiate(RMSvcEndpt,
iEndpointDiscovery.ServerEntry,
300000,
(uint)ContextOptions.EnableJournalDataAccess, //HDA
(uint)System.Threading.Thread.CurrentThread.CurrentCulture.LCID,
Guid.NewGuid().ToString());
if (iContext != null)
{
//find a read endpoint using the XiEndpointDiscovery connection
IEnumerable<ServiceEndpoint> readseps = iEndpointDiscovery.GetServiceEndpointsByBinding(typeof(IRead).Name, RMSvcEndpt.Binding.GetType());
//if we found at least one read endpoint, connect the context to it
readEndpoint = null;
if (readseps != null)
{
Console.WriteLine("Adding Read endpoint to Context\n");
ServiceEndpoint sep = readseps.ElementAt<ServiceEndpoint>(0);
readEndpoint = iContext.OpenEndpoint(sep, 30000, new TimeSpan(5000));
if (readEndpoint != null)
{
bReturnVal = true; //everything went OK
}
else
{
Console.WriteLine("Unable to add Read endpoint to Context\n");
bReturnVal = false; //failed
}
}
}
else
{
Console.WriteLine("Unable to open Client Context\n");
bReturnVal = false;
}
}
}
catch (Exception)
{
bReturnVal = false;
}
return (bReturnVal);
}
public bool CreateJournalList()
{
bool retval = false;
try
{
//create a new list of HDA objects for this read
// update buffer
// rate rate filterset(not used here)
iDataJournalList = iContext.NewDataJournalList(1000, 1000, null);
if (iDataJournalList != null)
{
//we need to add the list to a read endpoint to give it data access
iDataJournalList.AddListToEndpoint(readEndpoint);
//enable the list so we can connect the items we add to it and read data
iDataJournalList.EnableListUpdating(true);
retval = true;
}
}
catch (Exception)
{
retval = false;
}
return retval;
}
public void Cleanup()
{
if (iContext != null)
{
iContext.Dispose();
}
}
} //class DotNetSupport
}
namespace ConsoleFindObjectsHDA
{
public class DVServerAttributes
{
//some DeltaV-specific OPCHDA attributes
public static uint DELTAV_DESC = 2147483650;
public static uint DELTAV_ENG_UNITS = 2147483651;
public static uint DELTAV_EU100 = 2147483666;
public static uint DELTAV_EU0 = 2147483667;
public static uint DELTAV_DVCH_LAST_DOWNLOAD = 2147483682;
public static uint DELTAV_DVCH_ON_SCAN = 2147483683;
public static uint DELTAV_NAMED_SET = 2147483698;
}
}
My code:
public class CLASS_A {
public static Dictionary<int, CLASS_A> List = new Dictionary<int, CLASS_A>;
public static PP_CLASS pp = null;
public static CLASS_A ID
{
get
{
int key = get_threadID;
if (List.ContainsKey(key))
return List[key];
else
return null;
}
set
{
int key = get_threadID;
List[key] = value;
}
}
public virtual void init(lib, name)
{
...
if (name != "")
{
if (pp == null)
PP = this;
}
...
}
}
So whichever thread calls init, it's id is used to store this (whoever called). Eg my list looks like this:
45 = CLASS_A_object0
67 = CLASS_A_object1
...
But now when a different thread calls a method on pp, say CLASS_A.pp.setWelcome, this will return null for pp, and throws null exception! Because when set is called the thread id will be different and won't be in the list.
So is it possible that I know which object called so that I can do reverse lookup? Or maybe a different solution?
Why I want this:
Initially we were connecting to one device so that was ok. Now there are multiple devices with each one having its own ip/port. Initial code had just public static PP_CLASS pp = null; So others will be just calling methods on pp using class name and things were good.
Previous behaviour: The software picks list of devices from a file and since pp is static it only talks to the first device. I added that pp==null line which i forgot in my initial post. So when the code starts pp==null will be true and first device is assigned, but now for other devices pp==null will be false and thus I am not able to talk to other devices.
Please let me know if more details are needed.
Beginning with C# 5.0 (August 2012) there is a new feature "Caller Info Attribute". If your classes are stored in separate files, you can make use of the CallerFilePathAttribute to register which class actually has called.
Example from MSDN:
// using System.Runtime.CompilerServices
// using System.Diagnostics;
public void DoProcessing()
{
TraceMessage("Something happened.");
}
public void TraceMessage(string message,
[CallerMemberName] string memberName = "",
[CallerFilePath] string sourceFilePath = "",
[CallerLineNumber] int sourceLineNumber = 0)
{
Trace.WriteLine("message: " + message);
Trace.WriteLine("member name: " + memberName);
Trace.WriteLine("source file path: " + sourceFilePath);
Trace.WriteLine("source line number: " + sourceLineNumber);
}
// Sample Output:
// message: Something happened.
// member name: DoProcessing
// source file path: c:\Users\username\Documents\Visual Studio 2012\Projects\CallerInfoCS\CallerInfoCS\Form1.cs
// source line number: 31
You could try examining the Stack Trace.
var trace = new System.Diagnostics.StackTrace();
or to get the calling line only it should be something like:
var caller = new System.Diagnostics.StackTrace().GetFrame(1)
I have a class that I am using below. And I am using this class for my windows application. However, when I call the method from my application ReadInConfig() it successfully reads and fills the datatable, and assigns the _sip_ip address.
In my windows application I have the following. However, it doesn't give me the sip_ip that it has been assigned.
ConfigSIP readIn = new ConfigSIP();
readIn.ReadInConfig();
string sip_ip = readIn.sip_ip(); // Get nothing here.
I am thinking as the _sip_ip that has been assigned by the data table is a different object than doing this readIn.sip_ip();
Is there any way I can solve this problem?
Many thanks,
public class ConfigSIP
{
private string _sip_ip;
// Fill the data table and assign the sip ip.
public void ReadInConfig()
{
DataTable dt = new DataTable("Admin");
dt.ReadXmlSchema(#"C:\Config.xml");
dt.ReadXml(#"C:\Config.xml");
_sip_ip = dt.Rows[0]["Sip_ip"].ToString();
}
// Return the sip ip address.
public string sip_ip()
{
return _sip_ip;
}
}
You forgot to call ReadInConfig:
ConfigSIP readIn = new ConfigSIP();
readIn.ReadInConfig();
string sip_ip = readIn.sip_ip();
If your code is copied verbatim your client code isn't calling the ReadInConfig() method. So the string will never get populated.