PLC Design

[hamdi.tn]

Hi everyone,
So i worked once on a PLC project involving NXP TDA5051A , it's amplitude modulation chip with UART interface , an easy to use solution but amplitude modulation are obsolete now compared to other technique and some problem i faced with signal delivered by TDA5051A a bit easy to get lost in noisy network.
So am using PLC again in an industrial environment and trying to choose between ST solutions or TI solutions, with the ST ones am a bit  with the price 10€ for some dedicated chip as for TI i didn't find a dedicated chip but solutions that include a PA and uC, i didn't much reading yet for it and am not sure if that uC can be used for the main task and for PLC communication or it's just for com and need an other one to perform any other task that the equipment to design will do.
So anyone used a TI or ST solution ( or any other semiconductor manufacturer solutions) for a PLC can give his opinion about it / suggestion / recommendation   
this can be a feedback for PLC chips that no manufacturer will be aware of 

[hamdi.tn]

no feedback at all

[tonyarkles]

no feedback at all

What are you trying to accomplish? PLC is a term with multiple meanings: programmable logic controller, power line communications, etc.

You haven't really asked any specific questions that someone can help you with.

[hamdi.tn]

my bad i thought it's kind of obvious once i talked about modulation and network ... am talking about power line communication

[tonyarkles]

my bad i thought it's kind of obvious once i talked about modulation and network ... am talking about power line communication

So go ahead and ask a question Something in the form of "I'm trying to do X, and I'm not sure if I should Y or Z?" or "I've tried X and ended up with result Y, while I was expecting to get result Z. Does anyone know why?" usually works pretty well.

Tell us what you're trying to do, tell us what you've tried, and we can help you figure out how we might be able to help.

[hamdi.tn]

  am i speaking chinese , it's all in the first post but here it's in an other way
- i used PLC modem NXP TDA5051 before, it did what it did , was easy but not great communication performance.
- for a new plc project am trying to choose between ST or TI solutions
- what am asking is the experience of ppl who happened to work with one of them/ both , that may help me choose a way
any hep will be appreciated thanks 

[SL4P]

I think what the responses are saying is that you can use any platform to do anything.... but you need to clarify what the exceptions are which will place one above another.

In your application the greatest immediate challenge is the power-line interface and specific modulation parameters - then you can explore methods to generate the inputs to that.

i.e. Once you have defined the outputs, start listing the required capabilities and you can identify the inputs.

[hamdi.tn]

I think what the responses are saying is that you can use any platform to do anything....

i don't think so 

you need to clarify what the exceptions are which will place one above another

okay 

-This plc network should work in industrial environment -> is their any normative thing that particularly apply
-The plc networkis in star topology with one master and Indeterminate number of slave ( i guess this is an addressing detail can be solved by protocol)
-Distance between master and each slave can go up to 120m
-Power line used are 230VAC and can pass up to 10A to their load
-Those load are placed between the master and the slave , so the slave physically represent the far end of a power line

Edit : Bus topology

[SL4P]

OK, so we're getting there...

(I'll admit this is not my area of expertise - but these are the questions I'd be asking of I was facing a similar problem...)

I'll be a bit facetious for a moment.
The master needs to talk to the slave - hence they either need to perform the modulation themselves, or use a power-line interface to get the data up onto the mains phase.  Either one will need to be type-approcved by the supply utility for fail-safe, isolation and other concerns.

So there are no other inputs or outputs (analog, serial, etc)
What does the solution do? blink a LED at the slave?
Master sends, slave receives.  (Does slave return data or initiate conversations?)

Using power for data reticulation is a dubious idea at best, but in an industrial (or almost any) environment - may easily lead to excessive RF emissions.   Keep in mind that all your connected devices must be on the same (antennas) power phases as well - or have bridges fitted in the power distribution sub-boards.

What sort of data rates do you need? You mention AM in the first post, but this may limit your scope - and legality - (depending on your country & jurisdiction) - and will be more difficult to bridge accoss phases.

[hamdi.tn]

The master needs to talk to the slave - hence they either need to perform the modulation themselves, or use a power-line interface to get the data up onto the mains phase.  Either one will need to be type-approcved by the supply utility for fail-safe, isolation and other concerns.

that's exactly the purpose of the first post, i talked about the TDA and that's a chip that perform the modulation as a power line interface, ST propose the same thing for higher bit rate and different signal modulation form ( i think it's phase shift modulation ) the TI don't have a dedicated chip but a module that include a power amp and a uC/DSP with software that perform modulation and demodulation.

So there are no other inputs or outputs (analog, serial, etc)
What does the solution do? blink a LED at the slave?
Master sends, slave receives.  (Does slave return data or initiate conversations?)

yeah there is, slave in fact collect temperature and send them back to the master when asked, the master collect and send data to a PC via USB or serial interface so appart the communication part, nothing special about the app

Using power for data reticulation is a dubious idea at best, but in an industrial (or almost any) environment - may easily lead to excessive RF emissions.   Keep in mind that all your connected devices must be on the same (antennas) power phases as well - or have bridges fitted in the power distribution sub-boards.

What sort of data rates do you need? You mention AM in the first post, but this may limit your scope - and legality - (depending on your country & jurisdiction) - and will be more difficult to bridge accoss phases.
[/quote]

not much at all, data package at most include headers address and 4 bytes data checksum , no need for more and temperature acquisition is not that frequent 1 / min is way more than enough

i mention amplitude modulation as the way TDA5051 that i used before transmit data over power line , it's 120Khz amplitude modulation chip, the problem with it is when i used it in some particular situation the signal is totally attenuated even being far from noise source. so am not really enthusiast to use it again with this application.

[hamdi.tn]

Update : after looking at both ST and TI documentation am going with ST7540 , it's more available that ST7590 ( more sophisticated and higher performance ) with no US export restriction what ever the hell that mean ( as mouser say )

[ignator]

Quote from: hamdi.tn on March 01, 2015, 07:03:03 PM

Update : after looking at both ST and TI documentation am going with ST7540 , it's more available that ST7590 ( more sophisticated and higher performance ) with no US export restriction what ever the hell that mean ( as mouser say )

Hamdi.tn, I'm curious what your industrial application is. I don't see where you've indicated a bit rate. Do you have any availability requirements, or is this just for monitoring, not controlling the equipment?
I proposed a system for avionics use (in my past life). But in my case each power connection would be isolated from other loads, and the data would be diplexed onto this power via a data switch. It would be bidirectional, and 12Megabit was the design goal. It's pretty tough to do this with a star topology unless you can take control of the source and load impedances of your system power and loads.  I don't see doing this without filters to make the power system (source and sink) look high impedance to your serial diplexed data, or it will be attenuated into the noise.

[hamdi.tn]

hi ignator
it's just for monitoring, no control , the thing is a simple thermometer that send temperature data from his location to a single master in a control room, those slave have no control capability, bit rate is not critical, for problem related to PHY layer ST7540 is sufficient.
yap the power system impedance is the annoying thing about it,
it's bus topology, i should correct this in the previous post.
as you said for your application, i saw a system where they isolate each segment with a transformer and filter, i may end up using that too.

[DyslexicEng]

Hi hamdi.tn

I understand your first post and I understand what you were asking. I would have recommended the ST chip. I see that you went for the ST7540 back in 2015 due to availability. Now the ST7590 has become more available and it is the chip I want to use. But I have a lot of questions. The ST7590 has OFDM functionality and I have read through the design guide and datasheet and it does not say how to select or change the modulating frequency.

My questions to you are:
Was the ST7540 an easy Chip to implement into your system?
Did you get the PLC to work better than the TDA5051A?
Was the communication line reliable?
Did you get the system tested with FCC test? If so did they pass? (FCC is the test in South Africa and a few other countries, not sure what your power line testing might be called.)

I have more questions, but if you could get back to me on these I would really appreciate it. I might switch to the ST7540 if the OFDM is  to get working.

Thank you for your time.

Kind regards DyslexicEng