Process Data Interpretation; Fig. 16 Basic Range Of A Process Data Value - Beckhoff EPP3504-0023 Short Manual

Product overview
3.3

Process data interpretation

The entire measurement range is constituted as follows with regard to the output of the cyclic process data:
Fig. 16: Basic range of a process data value
The channel for this box module features an option to set the measuring range either to the conventional
Beckhoff type, up until now: "nominal full-scale value = PDO end value: LegacyRange" or the new method
"technical full-scale value = PDO end value: ExtendedRange".
• For Extended Range mode, the following applies:
◦ technical full scale value = PDO end value 0x007FFFFF.
◦ for information purposes, the channel can measure up to approx. 107% beyond the nominal range,
although accuracy specifications etc. are then no longer valid.
◦ outside the nominal measuring range, the Overrange or Underrange bit is set.
◦ for further diagnosis, the error bit and the error LED are set if configurable limits are exceeded or
not reached. By default, the limits are set to the technical measuring range, although they can be
narrowed by the customer.
Example: In the 4...20 mA measuring range, the lower limit is set to 0 mA, although it can be
customized in the CoE by the customer, e.g. set to 3.6 mA, in order to enable earlier detection of
potential sensor faults.
◦ The Extended Range mode is the default setting for the box module ex works.
◦ The mode is defined through the non-periodic rational LSB step size and an integer end value.
This enables the step size to be used in a PLC program without a rounding error.
• For Legacy Range mode, the following applies:
◦ nominal full scale value = PDO end value.
◦ compatible with existing interface from EL30xx/EL31xx/EL36xx.
◦ Overrange/Underrange, Error bit and Error LED are set simultaneously if the nominal/technical
measuring range is exceeded or not met.
◦ can be optionally activated in the box module.
◦ this mode is defined by an integer end value; assuming that the LSB step is no longer a whole
number.
52 Version: 1.2 EPP3504-0023