topic SNMP help please? in LabVIEW

SNMP help please?

SimonGoodson — Mon, 08 Sep 2014 17:12:44 GMT

Hello,

I'm brand new to SNMP although I have used LabVIEW a couple of times over the last few years. Right now I am developing an application to test power supplies. We are using a Dell G756N switched PDU to power each supply. I've tried a couple of approaches to controlling it, and SNMP is the most promising so far. During my research I came across ManageEngine's free MibBrowser and I was able to find the latest MIB in Dell's firmware download here. I have been able to communicate with the PDU and turn outlets on and off so far, but I really need to integrate the PDU control into the LabVIEW application to automate the testing. I came accross Mark Yedinak's SNMP communication library and his APC PDU examples, the latest of which I have found are in this thread.

I tried to make a VI to test the communication in LabVIEW using the OID I got from MibBrowser, but it returns an error code of 2, noSuchName. The PDU is set to use v1 of SNMP and both the public and private communities have write+ access. I have tried it with and without the leading period, but without any success. I am using LabVIEW 2013 64-bit. Could someone please look at the information below and see what I might be doing wrong or what direction to take to troubleshoot it?

Thanks,

Simon

MIB Object ID:

.iso.org.dod.internet.private.enterprises.dell.pdu.pdusub.hardware.rPDU.rPDUOutlet.rPDUOutletSwitched.rPDUOutletSwitchedControlTable.rPDUOutletSwitchedControlEntry.rPDUOutletSwitchedControlCmd

.1.3.6.1.4.1.674.10903.200.2.200.130.1.4.1.4.1 : {1 or 2}

I added the .1 at the end for the index of the first outlet, and the 1 variable is instant on, while the 2 is instant off

Picture

VI:

Front Panel:

Wiring:

Link to SNMP Communications and APC_PDU.zip examples:

http://forums.ni.com/t5/LabVIEW/APC-UPS-with-desktop/m-p/2431528/highlight/true#M749059

For some reason I can't get the actual VI to attach itself. The MIB is in the archive too. Its in my dropbox here:

https://dl.dropboxusercontent.com/u/10871313/Power%20Supply%20Testing.zip

Thanks again

Re: SNMP help please?

SimonGoodson — Wed, 10 Sep 2014 11:26:07 GMT

Anybody?

Re: SNMP help please?

PhillipBrooks — Wed, 10 Sep 2014 13:35:38 GMT

In this thread, the originator of the SNMP lib mentioned that if you see NoSuchName in the error_sting, your OID is not defined correctly.

Re: SNMP help please?

SimonGoodson — Wed, 10 Sep 2014 15:28:38 GMT

Hi Pillip,

Thank you for replying. I'm not sure how to troubleshoot that. Do you have any ideas? I'm only an occasional LabVIEW user and brand new to SNMP. I'm willing to do the work, I'm just not sure what it is.

I'm using the same OID that is listed in MIB Browser, and MIB Browser is able to successfully communicate. Is there another tool that translates better? I've seen references to MIBs that aren't standard, and maybe that is where the disconnect is happening, but I don't know how to identify a non-standard MIB.

Thanks,

Simon

Re: SNMP help please?

PhillipBrooks — Wed, 10 Sep 2014 18:43:03 GMT

You might try loading wireshark to capture and parse the actual UDP message sent by the mibbrowser program.

There may be some index or instance component you need to set/change in your OID.

Make the LabVIEW OID match the working application's message and Bobs your uncle

Re: SNMP help please?

SimonGoodson — Wed, 10 Sep 2014 19:16:09 GMT

Thanks Phillip, I'll give that a shot.

Regards,

Simon

Re: SNMP help please?

SimonGoodson — Thu, 11 Sep 2014 18:44:26 GMT

I've switched to LV2014 32-bit and installed Wireshark. I'm still getting the same "noSuchName" error, but using wireshark it lists the packet sent by SNMP as a "Malformed Packet". I'm guessing that somewhere in the depths of the VIs something is wrong, but I'm not sure what. I created a small program to save the output of the MIB Walk VI and that ran fine. The OID that I am sending is listed along with the correct type of variable.

The Wireshark traces and MIB Walk are included.

Thanks,
Simon

Re: SNMP help please?

PhillipBrooks — Fri, 12 Sep 2014 11:08:16 GMT

I don't have a lot of time to look at it, but I compared the wireshark captures and it looks like the problem is in the OID.

There is this post where someone else who had a OID containing a large value had some problems, and Mark had provided a fix.

From what I can tell in the date/tiome stamps of the files, the LLB you have is later than the updated one that Mark provided to fix the problem.

My only suggestion would be to try the LLB in the link above and see if that solves the problem.

http://forums.ni.com/t5/LabVIEW/Help-with-SNMP/m-p/1328623#M541584

Re: SNMP help please?

SimonGoodson — Fri, 12 Sep 2014 14:43:03 GMT

I appreciate all the time you have taken, thank you. At your suggestion, I tried the older SNMP library, but I got the same results.

Could you tell me how you analyzed the packets from Wireshark and determined it was the OID, or point me to some reading? I was going to translate the hex to U8 and see if they match what should be coming out of the SNMP vi's. Is that correct?

Also, as I said before, I did an MIB Walk that worked completely and wireshark didn't list any malformed packets during the run. After comparing the sub-vi trees of the Walk and the Set program, here are the vi's that are exclusive to the set program, and the ones that are shared with the MIB Walk:

Exclusive vi's:

Set snmp Item(s).vi

SNMP Set Request.vi

SNMP Build Set Request Packet.vi

SNMP Build Set Sequence.vi

SNMP String to Type.vi

SNMP String to Smallest Int Array.vi

SNMP ASCII Hex String To Binary String.vi

Shared vi's:

SNMP Get Random Port Number.vi

SNMP Open Port.vi
SNMP Build OID.vi
SNMP Encode SubID.vi
Sequence length convert.vi
SNMP Get Response.vi
SNMP Parse SNMP Packet.vi

Parse SNMP Packet Header.vi
Parse SNMP Tuple.vi
byte array to number.vi
SNMP Type to String.vi
SNMP Byte Array to Int32.vi
SNMP OID to String.vi
SNMP Parse Sequence Data.vi
SNMP Type Num to Type String.vi
SNMP Close Port.vi

Thanks,

Simon

Re: SNMP help please?

SimonGoodson — Fri, 12 Sep 2014 18:08:33 GMT

I guess I'm following up my own post, but here is what I have found today:

The references I found and used for SNMP packet structure/encoding:

SNMP Programmer's Reference - SetRequest PDU

SNMP: Simple? Network Management Protocol (especially the graphic at the bottom)

And I figured out you could click on the different parts of the UDP packets in Wireshark to get some further explanation of what they represent. Awesome tool, thanks for pointing it out!

Comparing the "Outlet 1 Off" packet from MIBBrowser (MB) and my LabVIEW (LV) program:

UDP packet length on MB is 62, is 61 on LV, definitely a mismatch.
Both SNMP portions start at the same offset
SNMP version looks good in both packets
Community string in both packets looks good
both packets define the packet as a set request, although the LV on is one hex shorter
Set request ID on MB is 2, on LV is -7295. Seems strange, bears further investigation.
The Varbind List Type looks okay. Note that it starts one place later in the LV packet than the MB packet due to the size of the request-id in the LV packet.
The Varbind Type and length is correct in both packets (30 1a)
The OID is correct in both packets (type:06, length:15, value (2b 06 01 04 01 85 22 d5 17 81 48 02 81 48 81 02 01 04 01 04 01)
The value in the MB is correct (type: 02 [integer32] lenth:01 value: 02), but the LV packet only has one hex: 00

Things to investigate:

The request id: Is a negative number valid? Does that particular value mean anything? Generated by the accessible vi's or is it a product of the LabVIEW UDP implementation, or the underlying OS?
Why is the value conversion incorrect? Is it in the VI or truncated later?

Knocking off a bit early today to take care of other business. Further updates Monday.

-Simon

Re: SNMP help please?

SimonGoodson — Mon, 15 Sep 2014 16:39:58 GMT

Figured it out. Apparently I don't know how to type. I had both a leading and trailing space on the variable type. " INTEGER " instead of "INTEGER". I certainly don't remember typing it that way, but how else could it get there? At least I learned a lot.

Thanks Phillip!

Regards,

Simon

Re: SNMP help please?

PhillipBrooks — Tue, 16 Sep 2014 18:15:40 GMT

Glad to see you were able to figure it out.

Sometimes the problem is much simpler than it seems.

Re: SNMP help please?

boffyie — Thu, 04 Jun 2015 12:50:48 GMT

Hi Simon,

Im very new to labview and snmp myself. I am using a wind turine simulator (http://www.ni.com/example/31161/en/)on labview and want to get the perfomance metrics from this to be polled every 10 seconds from an element manager via a java program, which will eventually be put on a dashboard. Do you have any advice on how i could get this simulator to snmpwalk so i could create oids for each metric?

Any help would be such a great help!!

brendan

Re: SNMP help please?

Hooovahh — Thu, 04 Jun 2015 13:16:55 GMT

What does this have to do with the SNMP error the OP was asking about? If the answer is nothing, then create a new thread. If the answer is something then feel free to slap me in the face for missing something. I just don't see what the controls and design simulation example has to do with SNMP.

Re: SNMP help please?

AaronTheAE — Fri, 05 Jun 2015 14:03:55 GMT

SNMP isn't directly supported by National Instruments (http://digital.ni.com/public.nsf/allkb/4CD3625A939A77DE852564050047D3BD) but one of our alliance partners created a 3rd party toolkit specifically for connecting and sending requests through SNMP, found here (http://www.snmptoolkit.com/index.html). Other than that, if you understand the SMNP protocol well enough you could use the TCP/IP VI's within LabVIEW to interpret that protocol.

Re: SNMP help please?

SimonGoodson — Fri, 05 Jun 2015 14:53:41 GMT

Hi boffyie, I'm a little confused by your question. I'm missing a bunch of requirements to run the wind generator example, but it doesn't appear to have any SNMP code to support status updates, so you would have to write the code to trap SNMP messages and respond to them yourself. I may be able to figure it out eventually, but it would be a substantial time investment for me. If you want to poll the machine running the sim, then it isn't a LabVIEW issue. Whatever program you are using to monitor the machine needs to be configured and the machine itself would likely need some SNMP configuration. Sorry I wasn't much more help. Good Luck! Regards, Simon

SNMP help for a newby to labview

boffyie — Fri, 12 Jun 2015 18:23:24 GMT

Hi ,

I am trying to figure out how to use the free snmp communication toolkit posted by Mark Yedinak. I basically am running a simulated turbine, and want to use snmp walk so it will create OIDs to communicate with a manager. If anyone could help me get started or point me in the right direction that would be great

Thanks in advance!! Im realy stuck with it!!

Re: SNMP help for a newby to labview

c-RADAE — Mon, 15 Jun 2015 15:51:38 GMT

I see that this is already a solved post. You may have more luck by posting this on a new thread.

Conrad