Eurotherm 6100, User Manual

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100/180MM DISTRIBUTED GRAPHIC RECORDER: USER GUIDE
HA029324
Issue 11 Oct 14 Page 155
4.3.16 MASTER COMMS (Cont.)
CONFIGURABLE PARAMETERS
This section defi nes those parameters which are unique to user defi ned registers.
Value Shows the value returned from the selected register, as modifi ed by the scaling factor (if
any).
Function Code Allows Modbus function code 03 or 04 to be selected. In some implementations, the func-
tions of the two codes are identical. In others, the codes have different functions. See the
documentation supplied with the slave for a list of supported Modbus codes. For this instru-
ment see
section 8.2.1 .
Register A decimal number representing the required parameter’s location in the slave’s Modbus
Register map. This information must be determined from the documentation supplied
with the slave. For this instrument,
section 8.4 contains listings for a number of instrument,
groups, and input channels. For details of maths, totalisers etc., refer to the relevant option
description.
Data Type Select a suitable data type for the selected parameter (again from the slave documentation).
For this instrument, a list of relevant data types is given in
section 8.4 .
Scaling Whether Scaling appears or not is Model and Parameter dependent. If scaling is required,
the choice may be ‘Decimal Places, or High/Low, again according to Model.
‘Decimal Places’ allows a dividing factor to be entered. An entry of 1, divides the returned
value by 10. An entry of 2, divides by 100 etc. for successful implementation, there must be
a suffi cient number of decimal places defi ned in the ‘Max Decimal Digits’ confi guration fi eld
for the value to be displayed with the required precision. ‘None’ leaves the returned value
unchanged.
For some slaves, scale zero (scale low) is returned as value 0 and full scale (scale
high) as value 65,535 (Hex FFFF) with intermediate values having proportionate val-
ues. For example the value 15, would be represented as 32,767 (7FFF) for a chan-
nel scale 0 to 30, as would a value of 50 for a channel scaled 0 to 100, and a value
of 45 for a channel scaled 30 to 60. In order to convert this reading to an understand-
able value, a scaling factor must be entered. If the low and high scale entries match
the slave channel’s scale, the master reading will be the same as the slave’s reading.
Selecting ‘High/Low’ allows Scale low and Scale high values to be entered for the selected
parameter. If ‘None’ is selected, the process value is displayed as a proportion of 65,535.