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Any changes to KeepAlive recently in the ENC28/Cerberus?


In my Office Palms IoT experiment I have the device uploading data every 5 minutes, however recently the data has only been making it every 15 minutes and the other uploads fail and typically after a while the device just stops sending data. I’ve been trying different things lately until today when this annoyed me to the point of breaking out some network sniffers and routing the device traffic through a sniffer so I could see what the heck was going on. Interestingly it seemed that the KeepAlive stuff was causing me grief and I had to add a line in the code to turn it off:

//Copyright 2011 Cuno Pfister
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//See the License for the specific language governing permissions and
//limitations under the License.

//Developed for the book
//  "Getting Started with the Internet of Things", by Cuno Pfister.
//  Copyright 2011 Cuno Pfister, Inc., 978-1-4493-9357-1.
//Version 0.9 (beta release)

using System;
using System.IO;
using System.Net;
using System.Text;
using Microsoft.SPOT;

namespace Gsiot.PachubeClient
    public static class PachubeClient
        const string baseUri = "";

        public static void Send(string apiKey, string feedId,
            string sample)
            Debug.Print("Attempting upload to COSM");
            Debug.Print("time: " + DateTime.Now);
            Debug.Print("memory available: " + Debug.GC(true));
                using (var request = CreateRequest(apiKey, feedId, sample))
                    request.KeepAlive = false;              <<<<<<----- Added this line
                    request.Timeout = 5000;     // 5 seconds
                    // send request and receive response
                    using (var response =
                        Debug.Print("COSM Response: " + response.StatusDescription);
            catch (Exception e)
                Debug.Print("COSM Error: " + e.ToString());

            Debug.Print("COSM time finished: " + DateTime.Now);

        static HttpWebRequest CreateRequest(string apiKey, string feedId,
            string sample)
            byte[] buffer = Encoding.UTF8.GetBytes(sample);

            var request = (HttpWebRequest)WebRequest.Create
                (baseUri + feedId + ".csv");

            // request line
            request.Method = "PUT";

            // request headers
            request.ContentLength = buffer.Length;
            request.ContentType = @ "text/csv";
            request.Headers.Add(@ "X-PachubeApiKey", apiKey);

            // request body
            using (Stream stream = request.GetRequestStream())
                stream.Write(buffer, 0, buffer.Length);

            return request;

        public static void HandleResponse(HttpWebResponse response)
            Debug.Print("COSM Status code: " + response.StatusCode);

It now appears my data is going up every 5 minutes and not hanging (testing is still in progress however). This app has been running for the last six months or more and was doing really well until late March which makes me wonder if some code changes in the ENC28 module / Cerberus might have happened.


I noted same problem with inputstream coming from a post request to the board (HttpListener). The first request run fine, but from the second call ahead it doesn’t work any more. It seems that the stream is not closed for some reason.
I will try keepalive to off. Thank you Duke for suggestion.


I haven’t had to touch my Palm Monitor at all which is a first for the last month or so, so turning off KeepAlive seems to have had a big impact and my device is running properly again.


We didn’t change it, I do not think!