Rockwell Automation T8019 Trusted Process Control Algorithms - Manual (Page 2)

SDS-8019
Trusted
TM Industrial Control System
Trusted TM Process Control Algorithms-T8019
ICS Triplex
Technical data sheets are intended for
information and guidance. The Company
has a policy of continual product
development and improvement.
Specifications are subject to change
without notice. For latest information, visit
our Website:-
www.icstriplex.com
MASS FLOW COMPUTATION
MASS
FLOW
OUT
=P
P
T
C
Z
m
e
h
The mass-flow computation block provides the mass
flow corrected for the current operating conditions.
( )
( )
( )
+
+
Ч Ч Ч Ч Ч Ч =
273 T
14.7 P
h e m Z C OUT
=P is the differential pressure, P is pressure and T is
temperature. C, Z, m, e and h are intended to be
constant values. All parameters are of type REAL.
=P and P are in psi, T is in
0 C.
If T=-273, a divide by zero error condition is generated,
this is to increment the associated error counter and
the mass flow function is to return a value of -1. Over
and underflow conditions are to result in an output
value of -1 and increment the associated error counter.
DEVIATION ALARM
DEV_AL PV
SP
DEV
US
DEV
DS
DEV
HI
DEV
LO
The deviation alarm function block takes the current
process variable (PV) and set-point (SP), together with
the up-scale and down-scale deviation between the PV
and SP (DEV
US
and DEV
DS
respectively). PV, SP,
DEV
US
and DEV
DS
are of type REAL, both outputs
(DEV
HI
and DEV
LO
) are of type Boolean.
DEV
HI
= ( (PV – SP) DEV
US
)
DEV
LO
= ( (SP – PV) DEV
DS
)
If an overflow condition occurs during the execution of
the function, DEV
HI
is to be set to PV>0, DEV
LO
to
PV<0 and the “overflow” error counter is to be
incremented.
PV, SP, DEV
US
and DEV
DS
must be finite, i.e. not
±infinities or NaNs.