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Reference Manual
00809-0100-4696, Rev AA
September 2004
E-5
Rosemount 848L
Interlock An interlock switch is easily added as follows, where input 4 is the normally
closed interlock:
| |
| 1 2 4 Out1 |
+--| |--+--||--+--|/|-----------------( )--+ OUT1_EQ
| | | |
| | 3 | |
| +--||--+ |
| |
• The first expression is still OR(IN(2),IN(3))
• The top and final expression is now AND(IN(1),OR(IN(2),IN(3)),IN(4));
Enter the expression and test as above.
Permissive A permissive switch may be added, with or without the interlock, as shown,
where 5 is the permissive:
| |
| 1 2 5 4 Out1 |
+--| |--+--||----||--+--|/|-----------( )--+ OUT1_EQ
| | | |
| | 3 | |
| +--||--------+ |
| |
• The first expression is now AND(IN(2),IN(5))
• The second expression is OR(AND(IN(2),IN(5)),IN(3))
• The final expression is AND(IN(1),OR(AND(IN(2),IN(5)),IN(3)),IN(4));
Emergency Shutdown In ladder logic, this would be shown as a switch for power to a section of the
ladder if there was more than one thing to be turned off. In the 848L, one
contact must be shown for each rung but only one input is required. The
shutdown contact is input 8 in the drawing below:
| |
| 1 2 5 4 8 Out1 |
+--| |--+--||----||--+--|/|----|/|----( )--+ OUT1_EQ
| | | |
| | 3 | |
| +--||--------+ |
| |
• The first expression is still AND(IN(2),IN(5))
• The second expression is OR(AND(IN(2),IN(5)),IN(3))
• The final expression is
AND(IN(1),OR(AND(IN(2),IN(5)),IN(3)),IN(4),IN(8));