377
5-33 Special I/O Instructions
The Special I/O Instructions are used to write data to or read data from Special
I/O Units, such as an ASCII Unit. Refer to the operation manual of the Special I/O
Unit for details on the use and content of data transfers.
5-33-1 I/O READ: READ(190)
Variations
j
READ(190)
(190)
READ
N
S
D
S: Source word
CIO
D: 1
st
destination word CIO, G, A, T, C, DM
N: Words to transfer
CIO, G, A, T, C, #, DM, DR, IR
Operand Data Areas
Ladder Symbol
When the execution condition is OFF, READ(190) is not executed. When the
execution condition is ON, READ(190) reads data from the memory area of the
Special I/O Unit allocated word S and transfers it to D through D+N–1. N indi-
cates the number of words to be read. S indicates the rightmost (first) of the two
words allocated for the Special I/O Unit (i.e., the input word).
This instruction cannot be used to read data from Special I/O Units mounted to
Slave Racks in SYSMAC BUS Remote I/O Systems. It can be used for certain
Special I/O Units mounted to newer version of SYSMAC BUS/2 Remote I/O Sys-
tems. Refer to page 34 for details.
N must be BCD. (Special I/O Units can transfer up to 255 words of data.)
S must be in the I/O Area and allocated to a Special I/O Unit.
If the ER Flag (A50003) or CY Flag (A50004) is turned ON, the instruction will not
be executed.
If the data cannot be sent or the Special I/O Unit is busy, the data will be trans-
ferred during the next cycle. To make sure that READ(190) execution has been
completed, check EQ (A50006).
A maximum of two READ(190)/WRIT(191) instructions can be used for Slaves
connected to the same Master. If a third instruction is attempted when two
instructions are already being executed, the third instruction will not be executed
and the Carry Flag (A50004) will turn ON. Be sure to control execution of these
instructions so that no more than two are being executed simultaneously for
Units connected under the same Master.
This instruction cannot be used to read data from Special I/O Units mounted to
Slave Racks in SYSMAC BUS Remote I/O Systems. It can be used for Units
mounted to Slave Racks in SYSMAC BUS/2 Systems as long as the the follow-
ing conditions are met.
1, 2, 3...
1. The lot number of the Remote I/O Master Unit and Remote I/O Slave Unit
must be the same as or latter than the following.
1992
October (Y: November; Z: December)
1st
01 X 2
2. The DIP switch on the Remote I/O Slave Unit must be set to “54MH.” (Only
four Slaves can be connected to each Master when this setting is used.)
3. The Special I/O Unit must be one of the following: AD101, CT012, CT041,
ASC04, IDS01-V1, IDS02, IDS21, IDS22, LDP01-V1, or NC222.
Description
Precautions
Special I/O Instructions
Section 5-33
Summary of Contents for CVM1D
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