RLL
P
LUS
Stage
Programming
7--9
RLL
PLUS
Stage Programming
DL105 PLC User Manual, 3rd Edition
Four Steps to Writing a Stage Program
By now, you’ve probably noticed that we follow the same steps to solve each
example problem. The steps will probably come to you automatically if you work
through all the examples in this chapter. It’s helpful to have a checklist to guide us
through the problem solving. The following steps summarize the stage program
design procedure:
1.
Write a Word Description of the application.
Describe all functions of the process in your own words. Start by listing what
happens first, then next, etc. If you find there are too many things happening at once,
try dividing the problem into more than one process. Remember, you can still have
the processes communicate with each other to coordinate their overall activity.
2.
Draw the Block Diagram.
Inputs represent all the information the process needs for decisions, and outputs
connect to all devices controlled by the process.
S
Make lists of inputs and outputs for the process.
S
Assign I/O point numbers (X and Y) to physical inputs and outputs.
3.
Draw the State Transition Diagram.
The state transition diagram describes the central function of the block diagram,
reading inputs and generating outputs.
S
Identify and name the states of the process.
S
Identify the event(s) required for each transition between states.
S
Ensure the process has a way to re-start itself, or is cyclical.
S
Choose the powerup state for your process.
S
Write the output equations.
4.
Write the Stage Program.
Translate the state transition diagram into a stage program.
S
Make each state a stage. Remember to number stages in octal. Up to
256 total stages are available in the DL105, numbered 0 to 377 in octal.
S
Put transition logic inside the stage which originates each transition (the
stage each arrow points
away
from).
S
Use an initial stage (ISG) for any states that must be active at powerup.
S
Place the outputs or actions in the appropriate stages.
You’ll notice that Steps 1 through 3 just
prepare
us to write the stage program in Step
4. However, the program virtually writes itself because of the preparation
beforehand. Soon you’ll be able to start with a word description of an application and
create a stage program in one easy session!
Summary of Contents for DL105
Page 2: ...DL105 PLC User Manual Manual Number D1 USER M...
Page 308: ...1B DL105 Error Codes In This Appendix Error Code Table...
Page 314: ...1C Instruction Execution Times In This Appendix Introduction Instruction Execution Times...
Page 324: ...1D Special Relays In This Appendix DL105 PLC Special Relays...
Page 327: ...1E PLC Memory In This Appendix DL105 PLC Memory...
