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CPU Unit Operation Section 10-1
Peripheral Servicing
Peripheral servicing involves servicing non-scheduled events for external
devices. This includes both events from external devices and service requests
to external devices.
Most peripheral servicing for CJ-series PLCs involved FINS commands. The
specific amount of time set in the system is allocated to each type of servicing
and executed every cycle. If all servicing cannot be completed within the allo-
cated time, the remaining servicing is performed the next cycle.
Note 1. Special I/O Units, CPU Bus Units, RS-232C communications ports, and file
servicing is allocated 4% of the cycle time by default (the default can be
changed). If servicing is separated over many cycles, delaying completion
of the servicing, set the same allocated time (same time for all services)
rather than a percentage under execute time settings in the PLC Setup.
2. In either of the Parallel Processing Modes for the CJ1-H CPU Unit, all pe-
ripheral servicing except for file access is performed in the peripheral ser-
vicing cycle.
10-1-3 Startup Initialization
The following initializing processes will be performed once each time the
power is turned ON.
• Detect mounted Units.
• Compare the registered I/O tables and the actual Units.
• Clear the non-holding areas of I/O memory according to the status of the
IOM Hold Bit. (See note 1.)
• Clear forced status according to the status of the Forced Status Hold Bit.
(See note 2.)
• Autoboot using the autotransfer files in the Memory Card if one is
inserted.
• Perform self-diagnosis (user memory check).
• Restore the user program. (See note 3.)
Units Servicing
Event servicing for Spe-
cial I/O Units
Non-scheduled servicing for FINS commands from CJ-series Special I/O Units and CJ-series
CPU Bus Units (e.g., requests to start external interrupt tasks)
Non-scheduled servicing for FINS commands from the CPU Unit to the above Units.
Event servicing for CPU
Bus Units
Peripheral port servic-
ing
Non-scheduled servicing for FINS or Host Link commands received via the peripheral or RS-
232C ports from Programming Devices, PTs, or host computers (e.g., requests to transfer pro-
gramming, monitoring, forced-set/reset operations, or online editing
Non-scheduled servicing from the CPU Unit transmitted from the peripheral or RS-232C port
(non-solicited communications)
RS-232C port servicing
Communications port
servicing
Servicing to execute network communications, serial communications, or file memory access
for the SEND, RECV, CMND or PMCR instructions using communications ports 0 to 7 (internal
logical ports)
Servicing to execute background execution using communications ports 0 to 7 (internal logical
ports) (CJ1-H and CJ1M CPU Units only)
File access servicing File read/write operations for Memory Cards or EM file memory.
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