How to identify sing ploarity of a channel

[sunilpadikar77]

Hi,

how do i identify sign ploarity of a channel? i need it because if sign is negative i have to multiply it with -1 before plotting.

Please help me on this?

Thanks,

Sunil Padikar M

[Brad_Turpin]

Hi sunil,

This could depend on the shape of your data channel.  Often if your polarity is negative, then the channel's minimum will have a greater absolute value than the channel's maximum, like this:

Set Channel = Data.Root.ChannelGroups(1).Channels("Speed")
IF Abs(CMin(Channel)) > Abs(CMax(Channel)) THEN
  Call ChnLinScale(Channel, Channel, -1, 0)
END IF

Another approach that is sometimes appropriate is to just take the absolute value of the whole channel, like this:

Set Channel = Data.Root.ChannelGroups(1).Channels("Speed")
Call Calculate("RawCh = Abs(RawCh)", Array("RawCh"), Array(Channel))

Brad Turpin

DIAdem Product Support Engineer

National Instruments