Re: Using get_float_dcba
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Olivier Barthelemy
Oct 10, 2016, 2:57:24 PM10/10/16
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From what i understand, it just determines the order in which the bytes are read from the receive buffer to be put in the output 4 consecutive bytes of the output float. It's up to you to chose the order based on in which order your slave sends data and the endinness of your master, both of which don't always respect a norm
Hello,
I have some confusion regarding get_float_dcba. I understand that it reverses the byte order. Given that the slaves are supposed to be big-endian and using IEEE754, does having to use _dcba imply that the slave is not to spec? Or is it because my PC is not big-endian, or have I miss-understood?
Thank you for your assistance.
Dave
-- I have some confusion regarding get_float_dcba. I understand that it reverses the byte order. Given that the slaves are supposed to be big-endian and using IEEE754, does having to use _dcba imply that the slave is not to spec? Or is it because my PC is not big-endian, or have I miss-understood?
Thank you for your assistance.
Dave
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David Barnard
Oct 10, 2016, 3:16:48 PM10/10/16
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OK thank you. Is it normal to try one, fail, then try the other? Or is there a more scientific approach?
btw I somehow managed to delete the thread on google groups when I was looking through the menus - sorry about that!
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Olivier Barthelemy
Oct 10, 2016, 3:27:43 PM10/10/16
to libmodbus
You could try setting a slave register to 0xaaBbccdd, reading it, and looking in which order you receive your bytes in the output float of the master, then deduce if you need the other float reading method?
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