Implementation of a digital cam controller

To trigger sequences highly dynamically and synchronously to a rotating or linear motion, a digital cam controller can be used. This means that a camera or a laser can be controlled on the basis of a position, for example.

The function "Switching with preset counter values" allows this, by appropriate parameterization, with position or time cams on a digital output track.

• Two digital outputs are available, representing two independent cam tracks, as both operate independently.
• Individual cams can be activated or deactivated independently on each track.
• Furthermore, cam positions can be changed per PLC cycle and direction-independent cams can be defined.

Implementation with up to four position cams

• Up to four position cams can be implemented, each with separate TRUE and FALSE threshold values.
• Two threshold values are required for each position cam to define the switch-on and switch-off position.
• If TRUE threshold value smaller FALSE threshold value:
  For all positions between switch-on and switch-off position the output is switched TRUE. For all other position values the output is FALSE.
  The switch-on position corresponds to
• in positive direction of rotation (CW) the TRUE threshold value,
• in negative direction of rotation (CCW) the FALSE threshold value.
• The switching behavior is inverted if TRUE threshold value greater than FALSE threshold value.

See examples in chapter "Switching with preset counter values":

• Example of a position cam with different counting directions
• Example for position cams synchronous to a linear movement

Implementation with up to eight time cams:

• Up to eight time cams can be implemented.
• Only one “Threshold” is required per time cam.
• When the time cam is reached, the output is switched TRUE (switch-on position) or FALSE (switch-off position) for the duration defined in “Duration” according to the specification for the “Output state”.
• If “Duration n = 0” for a time cam, the current “Output state n” remains active until the next time cam is reached.

See the example in chapter “Switching with preset counter values”:

• Example for three time cams