GE VersaMax PLC, User Manual

Page: 175 / 318

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10.7.1.4 Continuation Coils and Contacts
Continuation coils and continuation contacts are used to continue relay ladder rung logic
beyond the last column. The state of the last executed continuation coil is the flow state
used on the next executed continuation contact. If the flow of logic does not execute a
continuation coil before it executes a continuation contact, the state of the contact is no
flow. There can be only one continuation coil and contact per rung; the continuation
contact must be in column 1, and the continuation coil must be in the last column.
10.7.2 Relay Functions Coils
Coils are used to control discrete references. Conditional logic must be used to control the
flow of power to a coil. Coils cause action directly; they do not pass power flow to the
right. If additional logic in the program should be executed as a result of the coil
condition, an internal reference for the coil, or a continuation coil/contact combination
may be used. Coils are always located at the rightmost position of a line of logic:
10.7.2.1 References and Coil Checking
When the level of coil checking is set to “single”, you can use a specific %M or %Q
reference with only one Coil, but you can use it with one Set Coil and one Reset Coil
simultaneously. When the level of coil checking is “warn multiple” or “multiple”, each
reference can be used with multiple Coils, Set Coils, and Reset Coils. With multiple
usage, a reference could be turned On by either a Set Coil or a normal Coil and could be
turned Off by a Reset Coil or by a normal Coil.
10.7.2.2 Power Flow and Retentiveness
The following table summarizes how power flow to different types of coils affects their
reference. The states of retentive coils are saved when power is cycled or when the PLC
goes from Stop to Run mode. The states of non-retentive coils are set to zero when power
is cycled or the PLC goes from Stop to Run mode.
Type of Coil Symbol
Power to Coil Result
Normally Open -( )-
ON
OFF
Sets reference ON, non-retentive.
Sets reference OFF, non-retentive.
Negated -(/)-
ON
OFF
Sets reference OFF, non-retentive.
Sets reference ON, non-retentive.
Retentive
-(M)-
ON
OFF
Sets reference ON, retentive.
Sets reference OFF, retentive.
Negated Retentive -(/M)-
ON
OFF
Sets reference OFF, retentive.
Sets reference ON, retentive.
Positive Transition
-(P)-
OFF→ON
If power flow into the coil was OFF the previous
sweep and is On this sweep, sets the coil ON.
Instruction Set Reference GFK-1503E User Manual 175
For public disclosure