Ir/Cio Bit Allocations - Omron SYSMAC C Series Operation Manual

Data Exchange with CPU Unit
READ/WRIT Execution Restrictions
1, 2, 3...

5-4-2 IR/CIO Bit Allocations

78
The completion of execution of the I/O READ and I/O WRITE instructions can be
determined by checking the status of the Equals Flag. The Equals Flag will be
ON when execution has been completed.
Flag
Equals Flag SR 6306
1. The differentiated versions of the READ and WRIT instructions cannot be
executed for Special I/O Units on SYSMAC BUS/2 Slave Racks. The READ
and WRIT instructions must be executed until the = Flag (A50006) turns ON
indicating that the execution is completed.
2. The READ and WRIT instructions cannot be simultaneously executed for
the same Special I/O Unit. In such cases, execute WRIT first, and after the
execution is completed, execute READ.
3. One SYSMAC BUS/2 Remote I/O Master Unit can simultaneously handle
up to two READ and WRIT instructions. If two READ and WRIT instructions
are executed for Units mounted to SYSMAC BUS/2 Slave Racks and an at-
tempt is made to execute a READ or WRIT instruction for a third Unit, the CY
Flag (A50004) will be turned ON without executing the third instruction.
4. Therefore, when continuously executing READ instructions, you can use
the READ and WRIT instructions for a maximum of two Special I/O Units
under each SYSMAC BUS/2 Remote I/O Master Unit.
5. Up to four SYSMAC BUS/2 Remote I/O Master Units can be mounted to the
CV1000 or CV2000. In this case, therefore, up to eight READ and WRIT in-
structions can be executed simultaneously.
6. Up to 255 words can be transferred using a READ or WRIT instruction.
If the program writes output data after parameters, design the program as fol-
lows: Even if an attempt is made to write output data immediately after parame-
ters, such as scaling upper and lower limits, upper and lower limits, and binary/
BCD mode settings, are written, the data may not be correctly written due to the
internal processing of the Analog Output Unit. For this reason, design the pro-
gram so that it writes output data at least 100 ms after parameters have been
written. Also, the Parameter Update Bit must be turned ON to make the written
parameters valid.
The Analog Input Unit communicates to the CPU Unit using two-word mode
addressing. The I/O READ and I/O WRITE ladder instructions are used to read/
write data between the Analog Input Unit and the CPU Unit. The Unit requires
two words in the I/O table, one output word from the CPU Unit to the Analog Input
Unit, and one input word from the Analog Input Unit to the CPU Unit. The func-
tions of these words are described in the following tables.
C500 C1000H/C2000H
SR 25506
Section 5-4
CVM1/CV
A50006