# Reading ChunkEncoderValue from AT C5
**URL:** https://forum.commonvisionblox.com/t/reading-chunkencodervalue-from-at-c5/1398
**Category:** .Net API
**Created:** [April 26, 2021, 10:11am UTC](https://forum.commonvisionblox.com/t/reading-chunkencodervalue-from-at-c5/1398 "2021-04-26T10:11:57Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@kokostek](https://forum.commonvisionblox.com/u/kokostek)
#### Post date: [April 26, 2021, 10:11am UTC](https://forum.commonvisionblox.com/t/reading-chunkencodervalue-from-at-c5/1398/1 "2021-04-26T10:11:57Z")
Hi! I’m trying to read `ChunkEncoderValue` node from AT C5-1280 using .NET API:
```auto
var device = DeviceFactory.Open("GenICam.vin");
var deviceModeMap = device.NodeMaps[NodeMapNames.Device];
CvbStream stream = device.Stream;
stream.Start();
try
{
using (StreamImage image = stream.Wait())
{
var encoderValues = new List();
var scanLineSelector = deviceModeMap["ChunkScanLineSelector"] as IntegerNode;
for (var scanLine = scanLineSelector.Min; scanLine <= scanLineSelector.Max; scanLine += scanLineSelector.Increment)
{
scanLineSelector.Value = scanLine;
var encoderValueNode = deviceModeMap["ChunkEncoderValue"] as IntegerNode;
encoderValues.Add(encoderValueNode.Value);
}
}
}
finally
{
stream.Stop();
}
```
But accessing property `encoderValueNode.Value` throws error:
```auto
System.IO.IOException: 'IntegerNode[Std::ChunkEncoderValue]: Node is not readable.'
```
Why this node is not readable?
I can read this node using AT’s examples from `cxSupportPackage` with exactly the same camera settings.
I can read encoder value from chunk payload ([Using Chunk Mode Data with CVB.NET](https://forum.commonvisionblox.com/t/using-chunk-mode-data-with-cvb-net/333)). But I wanted to use vendor independed GenICam SFNC.
GenICam Browser is reading encoder values just fine. Seems like I’m missing something…
---
### Author:  [@Simon](https://forum.commonvisionblox.com/u/Simon)
#### Post date: [April 29, 2021, 1:32pm UTC](https://forum.commonvisionblox.com/t/reading-chunkencodervalue-from-at-c5/1398/2 "2021-04-29T13:32:42Z")
Hi kokostek,
the transmission of chunk data needs to be enabled inside the GenICam.vin-driver to be available over the api.
Also the “Chunk Mode” needs to be activated over the camera NodeMap:
Than your code should be working.
Note that transmitting chunk data might have a negative inpact on the performance.
---
### Author:  [@kokostek](https://forum.commonvisionblox.com/u/kokostek)
#### Post date: [April 29, 2021, 2:15pm UTC](https://forum.commonvisionblox.com/t/reading-chunkencodervalue-from-at-c5/1398/3 "2021-04-29T14:15:19Z")
Hi Simon,
thanks a lot for your solution. It works fine (I didn’t test performance yet though).
I just want to add my two cents regarding using GenICam.vin driver. One can also set `AttachChunk` programmatically if she opens device using `Discover`. I myself prefer `Discover` option as it permits to select device using info like IP address, etc. (not just CVB channel number). Here is the example:
```auto
// Select device by serial number, IP address, etc...
// Selecting first device here to be short.
DiscoveryInformationList foundDevices = DeviceFactory.Discover();
var selectedDevice = foundDevices[0];
// Set CVB color format to "Raw".
// I suppose we need this when working with chunks.
selectedDevice.SetParameter("PixelFormat", "0");
// Turn on "Attach chunk" parameter, so that chunk
// nodes become readable.
selectedDevice.SetParameter("AttachChunk", "1");
// Open device and configure chunk mode.
var device = DeviceFactory.Open(selectedDevice);
var deviceNodeMap = device.NodeMaps[NodeMapNames.Device];
var chunkModeActive = deviceNodeMap["ChunkModeActive"] as IBooleanNode;
chunkModeActive.Value = true;
// Read encoder value(s) along with image.
CvbStream stream = device.Stream;
stream.Start();
try
{
using (StreamImage image = stream.Wait())
{
var encoderValues = new List();
var scanLineSelector = deviceNodeMap["ChunkScanLineSelector"] as IntegerNode;
for (var scanLine = scanLineSelector.Min; scanLine <= scanLineSelector.Max; scanLine += scanLineSelector.Increment)
{
scanLineSelector.Value = scanLine;
var encoderValueNode = deviceNodeMap["ChunkEncoderValue"] as IntegerNode;
encoderValues.Add(encoderValueNode.Value);
}
}
}
finally
{
stream.Stop();
}
```
Credit to [this post](https://forum.commonvisionblox.com/t/how-to-get-cvb-color-format-programatically/767) for example of setting driver parameters.