GEM80-500 Series Controller
5. Programming
(08/04)
GEM80-500 Technical Manual (T2025En)
Page 5-15
5.6
Watchdog Trip Initiated by User Program
Watchdog trips initiated by the user program may be achieved by writing a non-zero
value into F1 and holding this non-zero code for at least one ladder scan. This is
achieved by enclosing the instruction to write to F1 in an obey block.
Refer to the GEM80-400 T1614 Technical Manual for more details and a ladder rung
diagram.
5.7 Data
Tables
The data tables consist of 16-bit binary words of data stored in the memory and
accessed by their address.
Each data table location may hold:
(a) 16 ON/OFF bits;
(b) A numerical value in the range -32,768 to +32,767.
5.7.1
Data Table Addressing
The data tables are addressed using the initial letter of the table followed by a number
e.g. G41 points to the word 41 in the G-table. If, for example, we were to look at the
content of data table address G1 it may be:
BIT
NUMBER
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
ACTUAL
VALUE 0 0 0 0 0 0 0 0 1 0 1 1 0 0 1 0
WARNING
The controller will automatically enter the RUN state when power is
applied if ALL of the following are true:
•
The Flash EPROM contains a valid User Program.
•
The front panel Mode Switch is set to ‘Flash EPROM Protect’ Position 1.
•
The on-board battery has been unable to maintain the RAM content
during power down.
The consequences of above happening are:
•
The controller will use the ladder program and P Tables contained in
the Flash EPROM and the watchdogs will close.
•
All other data tables including R and W tables will be set to zero
•
The fault log will be cleared.
•
The Real Time Clock will be set to 01/01/93 12:00:00
When the front panel Mode Switch is set to Position 0, the controller will
not enter the RUN state if the RAM content is corrupt.