Omron SYSMAC C Series Operation Manual page 92

Data Exchange with CPU Unit
Internal Processing and
Parameter Settings
1, 2, 3...
I/O READ Instruction – READ
I/O WRITE Instruction – WRIT
The C500-AD501 contains a processor that converts analog data and performs
advanced functions on the data. The following processing is performed.
1. RAM is initialized and internal diagnosis is performed with power is turned
ON.
2. Parameters are transferred from EEPROM to RAM. From this point on, the
Unit will operate using the parameters in RAM unless they are changed,
e.g., by executing the I/O WRITE instruction.
Note EEPROM contains the default settings for parameters when the Unit
is shipped from the factory.
3. The I/O WRITE instruction can be executed to change the parameters in
RAM. The parameters in EEPROM, however, will not be changed and any
changes to the RAM parameters will be lost the next time power is turned
OFF.
4. The parameters in RAM at any time can be written to EEPROM by using the
EEPROM Write Bit. Refer to 5-6-7 EEPROM Functions. The data written to
EEPROM will not be lost even if power is turned OFF.
5. RAM contains addresses 000 to 153. Addresses 000 to 045 are read-only
and are used to monitor operation. Addresses 046 to 153 are used to set up
or execute the various functions.
The I/O READ instruction can be used for all RAM addresses 000 to 153.
The I/O WRITE instruction, however, can be used only for RAM addresses
0046 to 153.
Note however, that the number of addresses that can be read or written with
the I/O READ/WRITE instructions in one operation is limited to 127. There-
fore, in order to read addresses 000 to 153 using the I/O READ instruction, it
is necessary to execute I/O READ twice. (Execute the I/O READ instruction
twice using the I/O WRITE instruction to set the beginning address that is
read.)
6. Input data is converted every 25 ms for all of the enabled input points. (Of the
16 input points, enable only the ones that are actually used.)
Note Using the advanced function can increase the conversion time to
greater than 25 ms.
7. The I/O READ and I/O WRITE instructions are used as shown below. Refer
to the Operation Manual for your PC for details on programming.
READ
W
S
D
WRIT
The function codes for the I/O READ and I/O WRITE instructions, READ and
WRIT, differ according to the PC, as shown in the table below.
Instruction
I/O READ instruction
I/O WRITE instruction
Number of words transferred
Specify word n + 1 allocated to the Unit.
Destination address
W
Number of words transferred
S
Transfer start address
D
Specify word n allocated to the Unit.
Mnemonic
C500/C1000H/C2000H
READ 88
WRIT 87
Section 5-4
Function code
CVM1/CV
190
191
77