I am looing for a way to split an encoder signal into two.

[mmervenne]

I am using a Heidenhahn linear encoder with a Heidenhahn Display. I would like to bring the quadrature input into a mtsubishi High Speed Counter module. The problem is that the only output from the Display is RS232. I would like to steer away from RS232. Does anyone know of a way i could split orsplice into the encoder signal between the encoder and the display to run to the High Speed Counter Card. Any help is Greatly Appreciated.

Mike

 

[Skogsgurra]

It probably won't work. The RS232 outputs a telegram that is read by the display. The contents of the telegram is the absolute position.

The HS counter needs an A+B encoder frequency input and there is no way to make the absolute position information from the encoder look like an incremental encoder output. (Except, of course, programming a fast micro to evaluate the difference between two readings and output quadrature signals corresponding to the difference. And that still will not be the same since you are not updating the position more often than telegrams are sent). Your best bet is to read the RS telegrams and convert them to parallell information that you input to a set of parallell ports. It does not need a very fast micro to do that and most micros have a built-in UART to do the reading. You still will not get the "feel" of an encoder, but it may be sufficient if the RS232 updates fast enough.

Personally, I would use one of the NewMicros "stamps". They have one with an ARM7 processor and it can be programmed in FORTH. Which is my favourite language. But any "stamp" can be used. Bear in mind, though, that the Basic stamps are quite slow.

Gunnar Englund

http://www.gke.org

 

[Barry1961]

I have split encoder signals between servo cards to tie groups of servo motors together many times. They were easy since the termination was already a terminal strip.

What is the input connection type to your current display?

Barry1961

 

[Skogsgurra]

Barry,

Read the OP. The output is an RS232 signal going to a display. He wants an encoder signal sent to a HS counter card. It is not at all what you think. Not a question of splitting/buffering. No Sir.

Gunnar Englund

http://www.gke.org

 

[ScottyUK]

Hi skogs,

I read it differently - the signal between the encoder and the display - i.e. the input signal to the display - is where he is enquiring about splitting the signal. The RS232 is the output of the display.

mike,

Assuming I'm reading your question correctly - a big assumption since it is 0100hrs over here! - here is my opinion:

It will depend to some extent on whether the signal is a voltage source, or an open collector type. If it is open collector then there may be a conflict between the inputs of the display and the input of the counter module. If the encoder sources voltage then providing it can drive the combined impedance of the display and the counter module it should just be a case of tapping off the signal. If the encoder uses open collector outputs then you may be able to connect an opto-coupler so the input is driven by the current sourced/sinked into either the display or counter and use the output of the opto-coupler to drive the other device.


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Your body might be a temple. Mine is an amusement park...

 

[sreid]

1) If the quadrature is differential RS-422 (as most are), there is no problem as RS-422 line drivers will drive many RS-422 receivers (as long as there is 0 or 1 terminator).

2) Heidenhain sells a spliter box (and cables) to do just that.

 

[Skogsgurra]

OK Scotty, I MAY have misread the OP myself.

But if there is a quadrature signal already, what's the question? This being an engineering site and mmervenne identifying himself as electrical makes me assume that he has already considered the obvious.

Gunnar Englund

http://www.gke.org

 

[ScottyUK]

Amen!



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Your body might be a temple. Mine is an amusement park...