I/O Read 2: Rd2(280) - Omron SYSMAC CV Series Operation Manual

Special I/O Instructions
Example
0000
00
0100
00

5-35-2 I/O READ 2: RD2(280)

Ladder Symbol
(280)
RD2
Description
Precautions
406
When CIO 000000 is ON in the following example, the number of words speci-
fied in CIO 0001 is read through CIO 0003 (the I/O word allocated to the Special
I/O Unit) and stored at consecutive words starting at D00010.
The following program section uses a self-holding bit to ensure that the read op-
eration is executed even if the Special I/O Unit (or Slave Rack) is busy when
READ(190) is executed. The type of programming is also effective when the
read operation requires more than one cycle. The Equals Flag, which turns ON
when the reading operation is completed, is used to end the execution.
(190)
READ 0001 0003
Equals
A500
Flag
06
Operand Data Areas
C: Control word
C S D
S: Source word
D: First destination word
When the execution condition is OFF, RD2(280) is not executed. When the ex-
ecution condition is ON, RD2(280) reads the memory contents of a Special I/O
Unit to specified words (beginning with D) in the Programmable Controller
through the source word ( S). The word specified for S is the third of the four
words (i.e., the first input word) that serve as the interface with the Special I/O
Unit.
The words that are to be transferred are specified by the control word. The con-
tents of the control word are as follows:
Control Word Contents
MSB
The beginning address to be read specifies the rightmost (lowest) word of the
range of data that is to be read from the memory area in the Special I/O Unit.
If 00 is specified as the number of words to be read, the instruction will not be
executed. If the sum of the beginning address to be read plus the number of
words to be read is more than 100 (binary), the Error Flag (A5003) will turn ON.
If an error occurs at the Special I/O Unit (such as, for example, a non-readable
area being specified), the Carry Flag (A50004) will turn ON.
The Equals Flag (A50006) can be used to check whether or not RD2(280)
execution has been completed.
Several cycles may be required before RD2(280) execution is completed. Dur-
ing that time, the execution condition for RD2(28) must remain ON.
D00010
0100
00
CIO, G, A, T, C, #, DM, DR, IR
CIO
CIO, G, A, T, C, DM
LSB
Number of words to be read (binary 00 to FF)
Beginning address to be read (binary 00 to FF)
Section 5-35
Address Instruction Operands
00000 LD 000000
00001 OR 010000
00002 READ(190)
D00010
00003 AND NOT A50006
00004 OUT 010000
(CVM1 V2)
0001
0003