Application and Installation Guide EMCP 4 SCADA Data Links
©2013 Caterpillar
All rights reserved. Page 15
NUMERICAL DATA
Numerical data is continuous real-world measurement data, such as temperatures, levels, pressures,
power, voltage, time, etc. In order to convert the bits of the received data into real-world data, the
following factors must be known:
Resolution (or scaling) – multiply the raw data by this first, to get scaled data
Offset – add this to the scaled data to get the correct measurement data
Data range – valid measurement data is within this range
These are given for each numerical data in Appendix A.
To troubleshoot or determine why certain data is outside of the data range, see section 6.3.
STATE-BASED DATA
State-based data represents a fixed set of states, such as True, False, Run, Auto, Stop, etc. For each
data point, each state must be assigned a value. The bits of the data correspond to one of those values.
A special case of state-based data is bitwise data, where each bit corresponds to a two-state value
(true/false, on/off, open/closed, etc). In this case, each register could represent as many as 16
independent two-state values.
The states and their values for each state-based data are given in Appendix A.
COMPLEX DATA
Complex data is aggregate data that is actually made up of multiple pieces of data. Those pieces, in turn,
can be numerical data, state-based data, or even complex data themselves. One example is time; time is
made up of years, months, days, hours, minutes, and seconds. Each of those pieces of data are
numerical in nature.
Complex data are defined in Chapter 5.
4.4 SECURITY
Security in SCADA is separate from security on the EMCP 4 display, but the access levels are parallels of
each other, and the passwords are shared. Data link security uses a different set of passwords than the
local security at the display. The EMCP 4 supports five levels of SCADA access, with increasing
permissions. Figure 4-1 below illustrates the different security levels.
NOTE: The display and SCADA can be at different access levels at the same time.
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