Eurotherm 6100, User Manual

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100/180MM DISTRIBUTED GRAPHIC RECORDER: USER GUIDE
HA029324
Issue 11 Oct 14 Page 115
4.3.11 FUNCTION (Cont.)
RATE-OF-CHANGE
The equation solved is:
Function
Rate of change of
Sample period
Rate Scalar
Units
Maths Number
Value Units
s
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Rate of change
0.125
Units
1) Channel 1
0.125
1) Math 1
0.0000
Figure 4.3.11n Rate of change confi guration menu
Where:
dPV/dt = Rate of change of PV with time
In
t
= Input value ‘this time’
In
t - P
= Input value ‘last time’ (i.e. ‘this time’ - P)
P = Sample period (i.e. ‘this time’ - ‘last time’) in seconds. Only periods that are a multiple
of 0.125 seconds are accepted.*
R = Scaling factor. Generally, R is the number of seconds in the required ‘per unit time’
value. For example: if R = 1, the rate is ‘per second’; if R = 60, the rate is ‘per minute’; if
R = 3600, the rate is ‘per hour’.
*Note: For channels being read over Modbus, the ‘priority intervals’ set in the Modbus Master
confi guration menu (
section 4.3.16 ) may cause the readings to be inaccurate or to be continuously
zero. For this reason, a minimum sample period of 1 second is recommended.
dPV
dt

In
t

In
t

p
P

R