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CScape Training classes

Class 1 (Unedited)

This is an unedited recording of class 1 (11/8/12) about the Horner CScape programming environment.

There are apparent blank times where I am explaining things on a white board and listening to questions from the floor.

 

If I get time, I will replace this with an edited version.

 

There are about 15 seconds of blank before the recording starts. - be patient!

 

 

Ladder Logic Boolean Elements  (Switches and Coils)
1 bit operators.

NO Contact

Standard Normally Open contact
This is a Normally Open digital input that can be an external switch wired to a digital input and named %Ixxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y

NC Contact

Standard Normally Closed contact
This is a Normally Closed digital input that can be an external switch wired to a digital input and named %Ixxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y

NO Coil

Standard Normally open coil
This is a Normally Open digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y or a screen labelled %Dxxx

NC Coil

Standard Normally closed coil
This is a Normally Closed digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y

Positive Transition Coil

Positive Transition Coil
This is a Normally Open Pulsed digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y
The relay pulses ON for one scan on a positive transition.

Negative Transition Coil

Negative Transition Coil
This is a Normally Open Pulsed digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y
The relay pulses ON for one scan on a negative transition.

Set Coil

Set Coil
This is a Normally Open Latched digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y
The relay latches ON and stays ON until a Reset coil is powered.

Reset Coil

Reset Coil
This is a Normally Open Latched digital output that can be an external relay or lamp wired to a digital output and named %Qxxxx, or an internal retentive relay contact labelled %Mxxxx, or an internal non retentive relay contact labelled %Txxxx, or a system flag labelled %Sxx, or a bit in a register labelled %Rxxxx.y
The relay latches ON and stays ON until a Reset coil is powered.

 

  • PLC  Scans operate from left to right on a rung, and top to bottom.
  • All Rungs MUST start with a switch or relay contact. If there is no need for an operating switch or relay contact, use a Normally Open Contact and label it as S7 (Always ON).
  • Contacts (Inputs) are at the left hand side of a rung.
  • Contacts can be connected in series, or in parallel (The first contact on a rung cannot be connected in parallel. – Use an S7 before parallel contacts if there is no other contact to the LHS.
  • Coils (Outputs) are at the right hand side of a rung.
  • Coils are connected in series. There is no limit to series coils on a rung.
  • Contacts can be reused many times.
  • Coils should only be used once in a scan except set coils, reset coils and pulse coils.
    If coils are used in more than one rung, the last one in the ladder program will dictate the state of the coil.
    If there are multiple rungs to drive one coil, use a new internal coil in each rung and then create a new rung with all the contacts in parallel driving the output coil.

Simple Direct On Line Starter Examples

DOL Starter Examples

Exercise

Design a DOL starter with a latching trip contact and reset button.

Design a reversing DOL starter with a latching trip contact and reset.
NB: Interlock the two contactors so that only one can be closed at any one time.

 

Class 2