Limit Values - Siemens SENTRON PAC4200 Manual

Description

2.8 Limit values

2.8 Limit values
SENTRON PAC4200 monitors up to 12 limit values as well as one limit that can be formed
by logically combining the other 12 limits.
Definition of the limit values
The number of limit values to be monitored is selectable. The following must be specified for
each of the maximum of 12 limit values:
● Limit value monitoring ON/OFF
● Monitored measured variable
● Threshold
● Upper or lower limit violated
● Time delay
● Hysteresis
Combination of the limit values
The limit value formed by the logical combination is called "LIMIT LOGIC".
SENTRON PAC4200 provides parameterizable logic for combining the limit values that
supports brackets, takes account of priority rules, and allows logical negation.
The logic is represented on the display using the graphic symbols familiar from digital
technology: Four logic function blocks are connected upstream of one higher-level logic
function block. Each of the upstream logic function blocks has 4 usable inputs.
Figure 2-7
The following logic operations can be selected for each logic function block:
● AND (AND operation)
● NAND (NOT AND operation)
● OR (OR operation)
● NOR (NOT OR operation)
● XOR (EXCLUSIVE OR operation)
● XNOR (EXCLUSIVE NOT OR operation)
34
LIMIT LOGIC
System Manual, 05/2019, A5E02316180B-05
PAC4200