Fix byte count when writing multiple coils#105
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OrangeTux merged 2 commits intoAug 27, 2020
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For full bytes, the Byte Count field was calculated too high:
8 // 8 + 1 = 2
while only one byte is needed to represent 8 coils.
Offset the values length before the truncating division to correctly
round to whole bytes. This is easier than what the standard
formulates:
N = Quantity of Outputs / 8, if the
remainder is different of 0 ==> N = N+1
Note that the actual data bytes were already handled with the correct
length. So in case of 8 coils, uModbus would send a Byte Count of 2,
but only one data byte before the checksum.
Put the Byte Count field after the Quantity, corresponding to the actual ADU layout.
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Fix off-by-one error in WriteMultipleCoils calculation. For full bytes, the Byte Count field was calculated too high:
8 // 8 + 1 = 2
while only one byte is needed to represent 8 coils.
Offset the values length before the truncating division to correctly
round to whole bytes. This is easier than what the standard
formulates:
N = Quantity of Outputs / 8, if the
remainder is different of 0 ==> N = N+1
Note that the actual data bytes were already handled with the correct
length. So in case of 8 coils, uModbus would send a Byte Count of 2,
but only one data byte before the checksum