User guide

Hardware
890 USE 108 00 August 2001 41
Reading
EEPROM System
Data
Data are read from an EEPROM card as part of the power-up sequence. If the
controller determines that a card is present in the socket, it checks the state of the
memory protect slide switch.
If the switch is OFF, the controller tries to read the data
If the switch is ON, the controller ignores the presence of the card.
If the controller attempts to read the EEPROM card but fails, it terminates the power-
up sequence and flashes the RUN LED on the front panel continually until you cycle
power.
Four flashes per second indicates that a checksum error was detected
One flash per second indicates that the user logic program is larger than the
available memory.
If the controller successfully reads data from the EEPROM card, it sets a flag in
system memory that prohibits any further writing to memory locations.
Memory locations may be written to after power is turned off, the EEPROM card
removed, and power turned on.
The EEPROM card will bring controllers up in the appropriate operating mode (RUN
or STOPPED). In A984-1xx, E984-24x/25x controllers, the mode may be selected
at EEPROM Write time. In 0984 controllers without a functioning battery, the
EEPROM card will always bring the controller up in STOPPED mode, and you will
need a DAP or programming panel to get it into RUN mode.
In both the A984-1xx and 0984, 0X and 1X references are enabled when the
controller is set to RUN mode after EEPROM download. 0X’s are cleared when the
controller goes to RUN mode and 1X’s are updated on the first scan. In A984
controllers, 4X references are zeroed if not saved to EEPROM. The document
packed with the EEPROM card (GI-MEEP-RMF) contains an illustration of user logic
that may be used to zero out the 4X registers in 0984 controllers.
EEPROM
Memory Program
Migration
Where controller memory limitations are not exceeded, the rules governing
EEPROM memory program migration are:
EEPROM programs from 0984 controllers can be loaded into A984-1xx
controllers.
EEPROM programs from A984-1xx, E984-24x/25x controllers cannot be loaded
into 0984 controllers because the 0984 controllers do not acknowledge 4x
registers and return an error.
A984-1xx, and E984-24x/25x controller EEPROM programs may be exchanged.
Note: The only other restriction may be due to the memory size of the individual
controller.