Feature Request

add conversion mechanism to modbus - similar to snmp

Opening a feature request kicks off a discussion.

Proposal:

add a conversion/scaling feature to modbus data

Current behavior:

some modbus devices keep an integer value in their registers that are a multiple of the actual value
i.e. "563" in the register represents an actual value of "56.3"

Desired behavior:

use a conversion factor, similar to the snmp input plugin. sample from snmp pasted below

Apply one of the following conversions to the variable value:

##   float(X) Convert the input value into a float and divides by the
##            Xth power of 10. Effectively just moves the decimal left
##            X places. For example a value of `123` with `float(2)`
##            will result in `1.23`.
##   float:   Convert the value into a float with no adjustment. Same
##            as `float(0)`.
##   int:     Convert the value into an integer.
##   hwaddr:  Convert the value to a MAC address.
##   ipaddr:  Convert the value to an IP address.
# conversion = ""

Use case:

when collecting from diverse data sources (snmp, modbus, exec scripts,etc) it would be beneficial to have the data uniformly formatted and scaled when storing them, to help simplify