Loop Data - Siemens Moore 353 User Manual

Data Mapping

7.3 LOOP DATA

Loop data is grouped into several categories. The groupings are not as significant when using the LIL option as all
LIL data has been mapped consistent with previous LIL products using Global and Non-Global data. However,
when using Modbus, the groupings enable single data requests (up to 60 Words/Registers or 48 Coils) to obtain
similar data with a single command. The loop will have different data if assigned as a controller type (i.e. using the
ODC block), a sequencer type (i.e. using the ODS block), an Analog Indicator Display (i.e. using the ODA block),
or a Discrete Indicator Display (i.e. using the ODD block), or Pushbutton/Switch Operation (i.e. using the ODP
block).
a) Dynamic data may change value on each controller scan and/or is not identified as being changed by the data
base change bit (coil). This category of data usually needs to be updated by a workstation every few seconds.
b) Variable data changes periodically. It is usually associated with on-line operation at a workstation but may only
need to be updated on a lower periodic basis or when a data base change is indicated.
c) Static data is similar to variable data but has a lower update requirement. The data may only need updating when
a change is indicated or to verify a previous change made to a parameter.
d) String data contains tag names, units, and messages.
7-6
UM353-1
March 2003