Monitor Comcast Motorola Arris Surfboard SB6141 with PRTG

I monitor my Comcast cable modem’s signal values in PRTG.

Set up Perl and get XML output from your modem

1. Install Strawberry Perl on the probe machine. This adds Perl.exe into the System-wide path.
2. Restart the PRTG Probe Service.
3. Grab prtg-cmstats-sb6141.pl from https://github.com/YandereSkylar/cabletools/ and drop it into C:\Program Files (x86)\PRTG Network Monitor\Custom Sensors\EXEXML.
4. Ensure you can get stats from your modem. By default, the modem is available at 192.168.100.1; you may need to add routing rules to your router to ensure you can access this. Hit http://192.168.100.1 in your browser, and then verify connectivity via perl prtg-cmstats-sb6141.pl from a shell on the Probe machine. You should get back a bunch of XML:

<?xml version="1.0" encoding="Windows-1252" ?>
<prtg>
<text> Up 0 days 0h:44m:3s</text>
<result>
<channel>Downstream Power Level</channel>
<customUnit>dBmV</customUnit>
<float>1</float>
<LimitMode>1</LimitMode>
<LimitMaxWarning>8</LimitMaxWarning>
<LimitMaxError>15</LimitMaxError>
<LimitMinWarning>-4</LimitMinWarning>
<LimitMinError>-15</LimitMinError>
<LimitWarningMsg>Signal level out of recommended range.</LimitWarningMsg>
<LimitErrorMsg>Signal level out of recommended range.</LimitErrorMsg>
<value>11</value>
</result>
<result>
<channel>Downstream SNR</channel>
<customUnit>dB</customUnit>
<float>1</float>
<LimitMode>1</LimitMode>
<LimitMinWarning>33</LimitMinWarning>
<LimitMinError>30</LimitMinError>
<LimitWarningMsg>Signal level out of recommended range.</LimitWarningMsg>
<LimitErrorMsg>Signal level out of recommended range.</LimitErrorMsg>
<value>37.8</value>
</result>
<result>
<channel>Upstream Power Level</channel>
<customUnit>dBmV</customUnit>
<float>1</float>
<LimitMode>1</LimitMode>
<LimitMaxWarning>50</LimitMaxWarning>
<LimitMaxError>55</LimitMaxError>
<LimitWarningMsg>Signal level out of recommended range.</LimitWarningMsg>
<LimitErrorMsg>Signal level out of recommended range.</LimitErrorMsg>
<value>42.5</value>
</result>
</prtg>

Get PRTG to Parse the XML Values

1. Because PRTG only offers you the EXE if it is present in the pre-determined directory (sigh), copy Perl.exe from the Strawberry Perl installation directory (usually C:\Strawberry\perl\bin) into C:\Program Files (x86)\PRTG Network Monitor\Custom Sensors\EXEXML.
2. Add an EXEXML sensor, set IP address 192.168.100.1 and set EXE/Script to Perl.exe in the dropdown.
3. Set Parameters field to "C:\Program Files (x86)\PRTG Network Monitor\Custom Sensors\EXEXML\prtg-cmstats-sb6141.pl" (include the quotes)
4. Write EXE result to disk in case of error.
5. Watch %PROGRAMDATA%\Paessler\PRTG Network Monitor\Logs (Sensors) to debug any error messages.
6. #profit.