THCAD-300 and Plasmac User Guide questions
- rodw
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I think the scale is looking for a really small number though. Everything you said makes it more clear, but I'm thinking it's looking for a really small number for scale though, would it be (1/83.375) = scale (0.011994)?
So you said you dropped the filter. Why? I'm still not sure I understand what the filter is supposed to do exactly.
Sorry, I was not near plasmac when I wrote the above so forgot it used the inverse of my calculation eg volts per frequency steps vs frequency steps per volt.
Pre-Plasmac, some people suggested to apply a low pass filter to the THCAD input. But when working with some of Dewey Garret's experimental work I was cautioned not to use filters as it could have undesirable affects. After testing, I never used a filter so dropped it out in future versions.
And yes, AgentWD40's calculator works fine!
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- phillc54
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Great, If Kyle gives the go ahead I will link to it in the docs and also reword the docs a bit. There is always something to do...And yes, AgentWD40's calculator works fine!
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- rodw
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Because then it would lock PlasmaC into one hardware vendor.I will definitely have to check that component out, I didnt know it existed. I thought to myself "why cant my frequencies and which THCAD I have just be part of the configuration?". I am sure there are lots of other things on the priority list though.
Well, it does not have to, you just need to add a few more fields in the configurator:
Selecting Use Mesa THCAD? could present a number of fields that allow calculating the scale and offset correctly. That would be cool as a lot of guys get hung up setting up the thcad.
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- AgentWD40
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Of course! I'm happy to contribute at least something.
Great, If Kyle gives the go ahead I will link to it in the docs and also reword the docs a bit. There is always something to do...And yes, AgentWD40's calculator works fine!
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- phillc54
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Man, this todo list just keeps growing...Well, it does not have to, you just need to add a few more fields in the configurator:
Selecting Use Mesa THCAD? could present a number of fields that allow calculating the scale and offset correctly. That would be cool as a lot of guys get hung up setting up the thcad.

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- AgentWD40
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Well, it does not have to, you just need to add a few more fields in the configurator:
Selecting Use Mesa THCAD? could present a number of fields that allow calculating the scale and offset correctly. That would be cool as a lot of guys get hung up setting up the thcad.
Phill, if you're interested in doing this I posted the formulas I used in the post that I linked to above.
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- phillc54
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Yes, I will take a look at it.Phill, if you're interested in doing this I posted the formulas I used in the post that I linked to above.
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- rodw
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Yes, I will take a look at it.Phill, if you're interested in doing this I posted the formulas I used in the post that I linked to above.
Also in my component
forum.linuxcnc.org/media/kunena/attachme...0660/scalethcad.comp
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- chimeno
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I'm trying to read the THCAD300 using an encoder with ethercat device, I was reading that I have to do the 0 - 300v scale, right? if someone can look at each other if the formulas are ok?
#define scale_frequency (100000)
// initialize variables
hal_data-> frequency_min = 115,700;
hal_data-> frequency_max = 914.600;
hal_data-> thcad_version_volt = 300,000;
double_t raw_frequency;
// read raw values
raw_frequency = EC_READ_S32 (& pd [hal_data-> frequency_pdo_os]);
// frequency to voltage conversion simple
* (hal_data-> frequency_khz) = raw_frequency / scale_frequency;
* (hal_data-> frequency_volt) = ((hal_data-> frequency_max - hal_data-> frequency_min) / hal_data-> thcad_version_volt);
* (hal_data-> thc_volt) = ((* (hal_data-> frequency_khz) - hal_data-> frequency_min) / (* (hal_data-> frequency_volt)));
greetings Chimeno
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