I am using jsmodbus npm library to retrieve 16 bit registers using readHoldingRegisters() function.
// array of values returned by jsmodbus readHoldingRegisters for two 16 bit registers
data = [ 17008, 28672 ]
I am using an ArrayBuffer and DataView to set and get the data in the required format:
const buffer = new ArrayBuffer(4)
const view = new DataView(buffer)
I understand that data returned from registers is always 16-bit integers split over two 8-bit byte values, so should I set the two bytes to the view as two consecutive ints even though it may be later retrieved from the view as an Int16 or Float32. Is this correct?
Secondly, if I expect to retrieve the data as signed Int16 or Float32, is it necessary to set the high byte as signed and the low byte as unsigned, like so:
view.setInt16(0, data[0])
view.setUint16(0, data[1])
And third: notwithstanding the need to set proper endianness, does it even matter which method you use when setting the data against the view, as the order of bytes and bits in the view isn't affected by which method you set against, only when you retrieve that data back out?
Certainly, it doesn't appear to:
view.setInt16(0, data[0])
view.setInt16(1, data[1]) // notice: setInt16
val = view.getFloat32(0)
// val = 122.880859375
view.setInt16(0, data[0])
view.setUint16(1, data[1]) // notice: set*U*int16
val = view.getFloat32(0)
// val = 122.880859375
Sanity check appreciated!
