Specifications

CONAX BUFFALO TECHNOLOGIES TSD 43.021
Rev. ORIG
Page 17 of 28
6.5 USER DEFINED TABLES
For applications where the input is non-standard and non-linear, a User Defined
Table (UDT) provides a simple and convenient way of linearizing an input to a
known set of datum.
Two methods are used for creating “User Defined Tables”. One is for
temperature sensors such as thermocouples and RTDs. The other is for inputs
such as mV, Volts, mA, resistance, and potentiometers.
The tables must be made in simple text (ASCII) files. These text files may be
written in, or transferred to, any standard text editor. Lines containing notes,
memos, comments, and descriptions must be preceded with an asterisk (*). The
asterisk signifies to the software that this line is not a part of the conversion table.
No letters, symbols or other characters are allowed in the data. See Table 2. It
is a good practice to include description, reference and other application notes in
the heading of the table proceded by asterisks.
It is highly suggested, although not required, that you use at least 141 points to
describe the sensor in the application’s range. This will ensure that the software
closely matches the sensor’s actual output and reduce the linearization error.
It may also be useful to open up a special directory for storing such tables in
order to facilitate easy access in future use. We also recommend using a .tbl file
extension in order to distinguish these special files from others.
6.5.1 UDT for Thermocouples and RTDs.
The conversion table should be formatted to contain two columns of numerical
values only. No letters, symbols or other characters are allowed in non-remark
lines. The first column is designated as the input column and should list the
temperature values in °C
in increasing order with identical increment values;
each subsequent number should be larger than the previous by the same
amount. The second column should be separated by a single space or TAB and
should list the corresponding sensor output values (mV for thermocouples and
Ohms for RTDs).
It is recommended to apply the simulator function (Reference Para. 8.0) in order
to verify that the input and output parameters correspond to the required values.
6.5.2 UDT for General Purpose Inputs
The first column should display the values of the actual sensor output in mV, mA,
Volts, Ohms or percent (%) for potentiometers. The second column should
display the corresponding values in engineering units. Display scaling, on the
main configuration screen, may also be applied to this table of engineering units.