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   Author  Topic: Where to start ?  (Read 5593 times)
Where to start ?
on: Feb 6th, 2007, 3:40pm
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We currently produce a Remote Data Logging solution that logs data and periodically 'sends' that data to a Control Room (or similar) via a UHF telemetry link.
The distance between remote data logger and Control Room has typically been anything from a couple of hundred metres to 20-odd kilometers.
Naturally, any data being transmitted from one place to another is subject to varying forms/degrees of corruption and, as such, the Control Room computer software has rather advanced (but, far more importantly, proven) error detection and control algorithms.
Some clients are now requesting that data be made available over some hundreds of kilometers - too far for UHF telemetry - but ideal for GPRS or Sat. Comm modules.
We have modified our solution's hardware to work with GPRS and transmit data to a known TCP/IP address and port. Our server, at this TCP/IP address and port, grabs the data and stores it in an SQL database - no problems.
The Control Room PC can then 'look-up' this data and request it be downloaded - so far all is just fine and dandy....
The problem arises when we receive corrupt data - because the data is arriving via the TCP/IP connection and not a serial port we CURRENTLY have no way of error checking it.... This is where the FabulaTech Network / Serial port thingy could come into play (at least I'm hoping it will....
If we could use a serial - network - serial adaptor thingy then the data could be sent / received EXACTLY as it is now (providing we set up / add a Serial-Network-Serial control layer (for  required TCP/IP addre and port etc) ) with all error correction algorithms functioning exactly as they do now AND we wouldn't have to create one solution for TCP/IP and one for serial/comm/legacy ports.
 
All sounds fine and dandy BUT :
[1] will the FabulaTech Network-Serial-Network thingy work ?
[2] how much does it cost (TOGETHER WITH OEM SOFTWARE INCLUSION FACLITY) ?
[3] Is it possible to have more than one TCP/IP addr/port in use on the one serial port ?
 
That's probably enough for now? Anyone able to point me in the right direction so that I may find answers to my (undoubtedly, rather mundane) questions please... I'd be eternally grateful.
 
Cheers chaps.
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Re: Where to start ?
Reply #1 on: Feb 7th, 2007, 2:30am
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Maybe I should be looking at the Virtual Serial Port Redirector Huh??
 
In our case I am happy (happier?) using an existing physical serial / comm. port. But I don't mind if it's virtual or 'real/physical'...
 
Still don't know where to start from really - buy some kit or...
 
Thanks in advance...
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Re: Where to start ?
Reply #2 on: Feb 7th, 2007, 11:06am
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Hi,
Very detailed post. Thank you.
Really, it seems Serial Port Redirector suits you better, but give me some time to understand your configuration completely. I'll email you ASAP.
One question, why the data could be corrupted?  
> because the data is arriving via the TCP/IP connection
> and not a serial port we CURRENTLY have no way of
> error checking it....
Do you mean the data is corrupting during transferring over network or before transferring? Please clarify.
Awaiting your reply.
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Andrew Scott

FabulaTech
===================
http://www.fabulatech.com
Re: Where to start ?
Reply #3 on: Feb 10th, 2007, 3:09pm
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Good evening Andrew,
Sorry for the lateness of my response to your question... 'why could the data be corrupt...'
In answer : to date we use a UHF comms link. There are probably a thousand reasons as to why the data arrives at its destination corrupt. Most common of which is someone else is using a similar frequency or producing a 'dirty' or high powered harmonic of their frequency which manifests itself on 'our' frequency and results in sporadic changes in character data or total loss of all or part of a data 'sentence', noty to mention range issues and local mechanical induced RF noise also.
It is NOT corrupt as it leave the transmitter (Data Logger) but becomes corrupt during transmission / reception... For whatever reason, the data leaves the Data Logger perfectly and with a known CRC/Checksum that is then extracted and compared to the checksum calculated at the receiver end upon reception. The two (in an ideal world with no corruption) would be the same, however, in reality there are occasions when they differ. The data is then flagged as 'dirty' and dealt with accordingly.
With regards to a TCP/IP connection, we (to be fair) don't often find the data's corrupt but rather missing in part or total with TCP/IP or UDP. Total loss is an acceptable risk and relatively easy to deal with. Partial loss is harder to deal with. Either way the CRC/Checksum data checks catches these errors and enables the receiver software to deal with the issue (re-request the data, dump the data, try to extract as much as possible etc...)
Having said all the above, how the data becomes corupt is rather immaterial. The fact remains we HAVE to check for data validity BEFORE attempting to use it... and this is why I'd prefer to use a serial to network to serial solution...
 
FYI : The F-T kit / code (DLL/ocx) will only be required at the Control Centre PC - not at the Data Logger (firmware).
 
QUESTION : If I begin to use the downloaded trial of Serial Port Redirector do I only get 15 days or is this negotiable? The reaason for my Q is that 15 days is not a long time for us integrate your solution well enough into our solution for us to trail  UNFORTUNATELY, WE CAN'T ALWAYS DEVOTE AS MUCH TIME TO THIS AS I'D IDEALLY LIKE AND, THEREFORE, OFTEN (AT LEAST UNTIL WE'RE FAMILIAR WITH THE KIT) WILL ONLY BE ABLE TO SPEND LIMITED TIME ON  ADAILY BASIS ON THIS ASPECT OF OUR SOLUTION... I hope you understand.
 
QUESTION : Do we also need a cable (serial / DB9 female plug to RJ45 socket)? Do we / can we make this (not a problem for us if we know the pin-out) or do you include one? I ask this because, how can we test the solution without interfacing our existing serial port to the web ?
 
QUESTION : OEM License. How does this work please and how much ? Typically I foresee us using just a couple of instances of your solution this year but snowballing to a hundred or so next year and then onwards and upwards (as they say) as we phase out the UHF transmission hardware...
 
Thanks in advance Andrew. Much obliged. If I could call you this would (at this stage) be MUCH quicker and simpler for us - just to get started ?
 
Either way, Thanks and speak soon.
Last Edit: Feb 10th, 2007, 3:16pm by Beachbum IP Logged

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