Filter
Top Products
FX Series Programmable Controllers Assigning System Devices 9
9-7
9.4 Real Time Clock Function
When one of the real time clock (RTC) memor
y
cassettes is used with either and FX or an
FX0N, the real time clock function of that PLC is then automaticall
y
enabled.
The time data of the RTC cassette is batter
y
backed. This means when the PLC is turned OFF
the time data and settin
g
s are not lost or corrupted. The duration or stora
g
e life of the time data
is dependent upon the condition of the batter
y
. The operation of the RTC clock circuits
consumes ne
g
li
g
ible currents compared with the RAM memor
y
(applicable to FX onl
y
).
The real time clock cassettes have a worst case accurac
y
of ± 45 seconds per month at an
ambient temperature of 25
°
C. The calendar function of the RTC cassettes caters for leap
y
ears durin
g
the period 1980 throu
g
h 2079.
FX PLC’s Pre Version 2.0
• These PLC’s do not support the RTC function.
Available RTC Cassettes:
Function Registers And Control Flags:
• Please see pa
g
e 6-3 for a list of the available clock devices.
• Please see section 5.14 (pa
g
e 5-138) for RTC supportin
g
functions with FX2N.
General Use Of Memory Cassettes
• FX and FX
2C
Main Processin
g
units can use an
y
of the available memor
y
cassette t
y
pes.
FX
0N
units can onl
y
use EEPROM or EPROM t
y
pe Memor
y
Cassettes and then onl
y
a
maximum of 2k steps can be accessed.
• It is necessar
y
to install a FX
0N
-40BL batter
y
to maintain the RTC time with FX
0N
controllers.
• The FX
2N
has a real time clock built in to the MPU. Althou
g
h it is possible to use the RTC
cassettes for memor
y
, it is not necessar
y
to use them to obtain the RTC function.
RTC Cassette Remark
FX-RTC Real time clock function onl
y
FX-RAM-8C
Real time clock function + 8K RAM
(Note: the FX
0N
cannot use this cassette,
because RAM pro
g
ram stora
g
e is not
g
uaranteed)
FX-EEPROM-4C
Real time clock function + 4K EEPROM
(Note the FX
0N
can onl
y
use 2K of the EEPROM)