10
DEVICE EXPLANATION
10.3 Internal System Devices
10.3.2 Special relay (SM)
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10.3.2 Special relay (SM)
(1) Definition
A special relay is used to store CPU module status data.
(2) Special relay classifications
Special relays are classified according to their applications, as shown in Table10.10.
: Usable special relay is included
: Usable special relay is not included
* 1 : In the Basic model QCPU, SM0 to 99 will be the area for error diagostics and SM100 to 129 will
be the area for a serial communication function.
* 2 : In the High Performance model QCPU, Process CPU or Redundant CPU, SM0 to 199 will be the
area for error diagnostics.
* 3 : Usable only when "Use the special relays/special registers SM1000/SD1000 and later" is selected
in the PLC system setting of the PLC parameter dialog box.
Remark
For details on special relays which can be used by the CPU module, refer to
Appendix 1.
Table10.10 Special relay classification list
Classification
Special relay
CPU module
Basic model
QCPU
High
Performance
model QCPU
Process CPU
Redundant
CPU
Universal
model QCPU
Diagnostics information
SM0 to 99
*1
SM0 to 199
*2
Serial communication
function
SM100 to 129
*1
System information
SM200 to 399
System clock/system
counter
SM400 to 499
Scan information
SM500 to 599
Memory card
SM600 to 699
Instruction related
SM700 to 799
debugging
SM800 to 899
Latch area
SM900 to 999
A Q/QnA
conversion
compatibility
SM1000 to 1299
*3
Process control instruction SM1500 to 1509
Redundant system (host
system CPU information)
SM1510 to 1599
Redundant system (other
system CPU information)
SM1600 to 1699
Redundant system
(tracking information)
SM1700 to 1779
Redundant power supply
module information
SM1780 to 1799