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6-1 PC Operation
This section details basic CPU operation of CV-series PCs. The CV-series
PCs can process instruction execution and I/O refreshing independently of
peripheral servicing. Independent parallel processing is called asynchronous
operation, and synchronized processing is called synchronous operation.
Select asynchronous or synchronous operation in the PC Setup.
6-1-1 Initialization
The flow of initialization on power-up is as follows:
1, 2, 3...
1. When power is turned on to the CPU, the first diagnostic program is run to
check hardware and memory.
2. If the system is set for transfer of the program and/or Extended PC Setup,
the data is transferred from the Memory Card.
3. All bits in memory except Holding Bits and bits set to be held in the PC Setup
are turned OFF.
4. All I/O Units, Remote I/O Units, and CPU Bus Unit connections are checked.
5. The section diagnostic program is run to check the I/O table, I/O bus, CPU
bus, and program memory.
6. All timer PVs are reset.
7. If the system is set to execute a power ON interrupt, an interrupt is generated
and the power ON interrupt program is executed.
8. Synchronous or asynchronous operation is entered as specified in the PC
Setup.
YES
NO
Power application
Clear IOM
Diagnostics I
Set for program
transfer?
Program transferred from Memory
Card to Program Memory.
(Turns OFF all bits except those in the
Holding Area, unless the IOM Hold Bit and
PC Systems Settings are set to retain IOM.)
Checks I/O Unit, Remote I/O Unit,
and CPU Bus Unit connections
(Checks hardware and memory.)
Diagnostics II
(Verifies I/O table and checks the I/O bus,
CPU bus, and Program Memory.)
Resets timer PVs
YES
NO
Power ON interrupt
program?
Executes the power ON interrupt pro-
gram if PC set for restart continuation.
Synchronous operationAsynchronous operation
PC Operation Section 6-1
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