Key Switches
Original instructions
About us
Overview
The low end CPUs have 1,435 kb of Flash EPROM memory, which can be used to save the program and the variables’ initial values. On power-up, if there is a program in Flash memory, you can choose one of three operating modes, using the PLC MEM switch on the CPU’s front panel. The 140 CPU 434 12A and 140 CPU 534 12A are equipped with a key switch with the Start, Mem Prt, and Stop positions. The 140 CPU 311 10 features a slide switch with the Mem Prt On, Not Used, and Mem Prt Off options.
Behavior on Power Up
The CPU’s behavior on power up is determined by the key switch position. The behavior could be:
WARNING
UNEXPECTED EQUIPMENT OPERATION
Always perform a Back Up Clear after an OS upgrade of the Quantum (140 CPU 534 •, 140 CPU 434 14A, 140 CPU 311 10) CPUs.
Failure to follow these instructions can result in death, serious injury, or equipment damage.
NOTE: To ensure a warm restart of an application following an OS upgrade on Quantum CPUs, click PLC → Project Backup... → Backup Clear.
This section describes the three positions of the rotary key switch, and their respective meanings.
Key Switch Figure
The key switch isolates memory from programming changes while the controller is in operation. The following figure shows the key switch.
NOTE: The key switch positions shown next to the left switch (above) are provided for reference only, and are marked on the module as indicated on the right.
NOTE: The 140 CPU 434 12A and 140 CPU 534 12A processors feature the key switch illustrated above, while the 140 CPU 311 10 has a slide switch.
Key Switch Description Tables
The following table provides key/slider switch information for these three low end CPUs.
CPU Type
Switch Position
Behaviour
Protected?
Accepts Stop or Start?
Key Switch Transition
Quantum 140 CPU 311 10
Mem Prt On
The application in Flash memory is not transferred to internal RAM; a warm restart of the application is triggered.
Y
N
From Mem Prt Off: does not modify last controller state and rejects programmer changes.
Not used
Do not use this position, because it may lead to undefined operation
Y
N
n/a
Mem Prt Off
The application in Flash memory is automatically transferred to internal RAM when the PLC is powered up. A cold restart of the application is triggered.
N
Y
From Mem Prt On : enables programmer changes and starts controller if stopped.
Quantum 140 CPU 434 12A 140 CPU 534 14A
Stop
The application in Flash memory is not transferred to internal RAM; a warm restart of the application is triggered.
Y
N
From Start or Mem Prt: stops controller, if running, and voids programmer changes.
Mem Prt
The application in Flash memory is not transferred to internal RAM. A warm restart of the application is triggered.
Y
N
From Stop or Start: inhibits program changes, controller run status is unchanged.
Start
The application in Flash memory is automatically transferred to internal RAM when the PLC is powered up. A cold restart of the application is triggered.
N
Y
From Stop: enables programmer changes, starts controller. From Mem Prt: accepts programmer changes, starts controller if stopped.
The following table provides information on switch position for low end Quantum 140 CPUs with firmware < 3.2:
Operation
Switch Position
Stop
Mem Protect
Start
Programming mode
Allowed
Allowed
Allowed
Monitoring mode
Allowed
Allowed
Allowed
Upload application
Allowed
Allowed
Allowed
Download, online modification
Allowed
Forbidden
Allowed
Stop command from Control Expert
–
Forbidden
Allowed
Run command from Control Expert
Forbidden
Forbidden
Allowed
Init command from Control Expert
Allowed
Allowed
Allowed
The following table provides information on switch position for low end Quantum 140 CPUs with firmware ≥ 3.2:
Operation
Switch Position
Stop
Mem Protect
Start
Programming mode
Allowed(1)
Forbidden
Allowed(1)
Monitoring mode
Allowed(1)
Allowed(1)
Allowed(1)
Upload application
Allowed(1)
Forbidden
Allowed(1)
Download, online modification
Allowed(1)
Forbidden
Allowed(1)
Stop command from Control Expert
–
Forbidden
Allowed(1)
Run command from Control Expert
Forbidden
Forbidden
Allowed(1)
Init command from Control Expert
Forbidden
Forbidden
Allowed(1)
(1): Password-protected if a password has been defined in Control Expert application