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IN2L, IN2H if available, are set according to the process signal
SPMD= PV1
Note: If PV1 are chosen for both SPMD and PVMD, an Error Code will appear. If PV2 are
chosen for both SPMD and PVMD, an Error Code will appear. The user should not use these
cases, otherwise, the Process Control Card will not control properly.
4.3.1.1.4.20 Differential Control
In certain applications it is desirable to control second process such that its process value
always deviates from the first process with a constant value. To achieve this, set the following
parameter in the Setup menu.
FUNC=FULL
IN1, IN1L, IN1H are set according to input 1 signal
IN2, IN2L, IN2H are set according to input 2 signal
IN1U, DP1, IN2U, DP2, are set according to input 1 and input 2 signal
PVMD=P1-2 or P2-1
SPMD=SP1.2
The response of PV2 will be parallel to PV1 as shown in the following diagram
Figure 4-51.Relationship Between PV1 & PV2 for Differential Control
The PV display will indicate PV1-PV2 value if P1-2 is chosen for PVMD or PV2-PV1 value
if P2-1 is chosen for PVMD. If the user needs PV1 or PV2 to be displayed instead of PV, they can
use the Display Mode to select PV1 or PV2 to be viewed
If PVMD selects P1-2 or P2-1, while SPMD selects PV1 or PV2, an Error Code will appear.
In this case the signals used for input 1 and input 2 should be the same unit and same decimal
point, that is, IN1U=IN2U, DP1=DP2, otherwise Error Code will appear.
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