Got a little confused on Max hops and Hops used

[ELA]

I could use a little help as I seem to have gotten myself a little confused on Max hops and Hops used.

I thought I understood them pretty well but need a little clarification that I cannot seem to glean from the Insteon Details doc.

 

Given that a PLM is commanded to send a standard Direct message as 3:3 (3 max hops and 3 remaining) initially.

The 1st response, direct from the PLM to the host, will be 3:3 and acked that is what will be sent.

 

In a pristine communications environment the intended receiver will "report" a 3:2 , and the response message back to the sender will be received with a 3:2.

This seems true from my testing and the fact that you never see a 3:3 in a response (0x50) message, in the ISY event viewer ( or do you?).

 

What am I missing? If you assume that the receiver can actually hear the primary sender on the very first transmission (prior to any retransmits) why does the response always contain 3:2 and never 3:3?

 

Its as if the initiator decrements the hops left when it first transmits its primary. But if this is the case then how would you ever get 3 true hops sent? The listeners would hear 3:2 , decrement count left/ retransmit once, next hears 3:1 , decrements count/ retransmits #2, and now a listener would hear 3:0 ( and not retransmit the third time).

 

I understand this if the receiver is actually "hearing" the the first hop (and not the primary xmit), but in a very pristine network shouldn't it actually be hearing the primary send, yet the response is as if it heard the 1st hop, indicated by the 3:2 contained in the message response?

 

We know a device can hear the primary send, due to the fact that if you send with 0:0 (0 hops allowed) you do get a 0:0 response message.

I somehow got myself a little confused. Any help here?

 

Based on this, if the receiver hears the primary transmission, why not give a 3:3 response ?

 

Is it such that any time there is one or more hops allowed that it is assumed one hop was used?

[LeeG]

Some additional information. I can confirm the observations regarding Hops Remaining. All of my observations over the years show Hops Remaining as 1 less than Max Hops (except where a retry is done). This is true even on one way observations. Press a paddle/button on a Controller and the inbound Insteon messages from the Controller to the PLM show Hops Remaining 1 less than Max Hops. The Group Broadcast message (3:2) is not ACKed and the Group Cleanup Direct message (1:0) is passed to the application before an ACK is sent back to the Controller. Both messages have the Hops Remaining 1 less than Max Hops.

 

Nothing objective regarding why. My belief is the messages leave the Controller with a 3:3/1:1 value but I have no objective proof.

 

Perhaps your test tool will be able to independently display an Insteon message some day!! Even as basic as the bit pattern would be major step forward.

[ELA]

Thanks LeeG,

 

I was going along just fine with my understanding of max hops and hops used, as in how we seem to agree, from our experiences.

Then I decided I wanted to be able to distinguish between when the receiver got the message on the primary send vs the very first hop (when initially sending a 3:3).

From what I am seeing you cannot using a (3:3) send? Since the Initiator decrements the hop count on the primary send, there is an implied- it was received on either the primary or the first hop, when you get the (3:2) response, but no clear definition as to which one it was.

 

I guess you have to send a separate (0:0) in order to determine whether the primary send is getting through.

 

I have done testing where I send a (3:3) msg from one test PLM ( in initiator mode) to a second test PLM (in monitor only mode). This enables me to see the message that the receiver receives and that test confirms that the initiator must have decremented the count since the received message decode is (3:2).

 

I had wanted to get this clear in my head before I posted some other results from a recent diagnosis. Anyone one else with knowledge contrary to the stated understanding would be greatly appreciated.

 

I do not have any plans to go a level deeper in an attempt to create an , "Insteon Data Line monitor". I think that would be totally awesome for those of us who have spend way too much time playing with Insteon

 

I have to say that the ELAM device as it now stands is a awesome test tool. It does not do everything but it could be a valuable addition to a persons Insteon tool box.

I have been using it for quite a while now in my testing. It is nice to be able to confirm results via the ISY diagnostics sometimes as well for confirmation.

 

Who among us can have too many tools?

[LeeG]

The PLM in Monitor mode is processing messages normally on the powerline side. It is the link database lookup that is changed. I think the receiver is decrementing the Hops Remaining count rather than the Controller starting out at 3:2. Of course I have no objective way to prove that. It would seem the Hops Remaining count would not work as described if the Controller started out at 3:2.

 

I love my toys!

[ELA]

Hi LeeG,

What you say makes total sense about the receiver decrementing the count, perhaps before it gets ready to simulcast the 1st hop, and before it reports the received message to the host.

 

I had assumed that the received message, as sent to the host (on the receiver end) would be a true image of the message actually received, but using your theory everything would then make more sense.

 

Going forward I could assume that the receiver decrements the count, and then somewhat erroneously inserts that hop count, as the actual received message that it reports to the host, even though it really received a (3:3)? I say somewhat erroneously because the message reported at the receiver is a (0x50) msg , not a (0x62) acknowledgement of a send.

 

Not sure what you meant by the link data base lookup being changed? I am not using any links in these test devices. Just direct message exchanges.

 

your theory works to keep everything straight in my head at least.