The history of the PLC by Dick Morley

1. March 2008
ISA Tampico, Mexico
Programmable Controller:
The Start of It All

8. Bedford Associates
 Skiing and Harley
 Out of the company
 Retired 1964?
 Contract engineering
 20 professionals

9. 1968
 New Year’s Day
 Hangover
 Late again
 Similarity across applications
 Lazy

10. Philosophy #1
 Heat
 Electricians
 Never off
 Over-engineered
 Coke proof
 Make money while I sleep

11. Philosophy #2
 Heat
 Memory
• Shannon
 Snapshot
 Grab – process – ship
• Intermodulation effects

12. Hardware #1
 No fans
 Conductive cooling
 Viewing the thermo world with copper
 Sealed
 Spark immunity – welding?
 Stunt – memory – process

13. Hardware #2
 No “off” switch
 Looks good to manufacturing
 Power voltage insensitive
 Rugged
 Cost is a bad word

14. Software
 For the electrician
• For the problem, not the academics
 Sample rate a constant
• Problem speed – not computer speed
• Quantum thinking
• A lump of energy in the power

15. Language #1
 Language
 Memory
• Shannon
 Hard real time
 Never wanted to repair
 Come from, not go to
 RLL

16. Language #2
 Standalone lines of logic
 No interrupt
 Relay, not Boolean
 Constant scan, independent of activity
 Only four contacts per line
 We got no respect from MIT

18. Market #1
 Not a computer
• Erased boards
 Started – CNC – not another piece of
colored sheet metal
 Angel – never original product
 Low hanging fruit – Ford

19. Market #2
 What is it?
• Box of relays – relays complexity
constrained
 Time to market
• Months to weeks
 Runs “forever”

20. Money
 Digital – Anderson – airport
 VC
 Almost failed

21. President
 Board chair
 Tech – Fletcher
 Sales – Rousseau
 Money – Kramer
• Paint story

22. Manufacturing #1
 The box
• Temp and spark
 Always on
 Harwood
 Big boards
 Move people

23. Manufacturing #2
 Real quality
 Overnight at temp
 Running in the box

24. Users
 GM story
• PDP – 16
• Never knew
 GE story
 Landis grinding
• Plane and crash – welding cable
• Japan – Yaskawa and Toyota

25. Competition
 After the fact
 GE OEM by Modicon
 Odo Struger
• Management vs. tech
 PDP-II, RT II
 Relays – backup?

26. Me
 Never an employee
 Temp president for
several weeks
 084 to 184
(Morley to Greenberg)
 Number and name –
job and Schwenk
 Machinist and physicist

28. My Guiding Principle