Precautions For Component Communications; Starting Communications With The Components - Omron CPM2C Operation Manual

Precautions for Component Communications

7-5-2

Starting Communications with the Components

1,2,3...
7-6

Precautions for Component Communications

Time Required to Refresh
Read/Write Data
Establishment of
Communications with the
CPU Unit
Operating Mode of the
CPU Unit
Switching the Simple
Communications Unit
from "Stop" to "RUN"
• When using CompoWay/F, set the starting addresses of each compo-
nent's read/write variable type areas.
2. When using CompoWay/F, set the variable type and variable address of
each variable that you want to read or write. (Set this information in the
read/write variable type area.)
3. When writing data, set the data that you want to write in the write data area.
Use the following procedure to start communications with the components.
1. Set the rightmost digit of the "Simple Communications Unit control" word
in the Control Data Area (the RUN/Stop digit) to 1 (RUN).
2. Turn ON the Read Command Bit or Write Command Bit of the desired
component. (These bits are in the Control Data Area with word offsets +3,
+4, +5, and +6. See Communications Control Bits on page 240.)
Changes to the following values are recognized only when the Simple Com-
munications Unit control word's RUN/Stop digit is switched from Stop to RUN.
When one of these values has been changed, switch the Simple Communica-
tions Unit from RUN to Stop and then back to RUN again.
• Segment information
• Command group
• Communications protocol
• Starting addresses of read/write data areas
• Starting addresses of read/write variable type areas
Note Refer to Simple Communications Unit Control on page 238 for details on the
RUN/Stop Digit.
Observe the following precautions when communicating with components.
The time required to refresh read or write data varies with the CPM2C's cycle
time. Moreover, the refreshing interval is not fixed.
Power is supplied to the Simple Communications Unit and the CPU Unit at the
same time. After the power is turned ON, the Simple Communications Unit will
attempt to establish communications with the CPU Unit and will wait for a
response. If there is no response from the CPU Unit after retrying for 2 min-
utes, a fatal error will occur and the ERR indicator will light.
It is not possible for the Simple Communications Unit to write data to the CPU
Unit if the CPU Unit is in RUN mode. Just before writing data, the CPU Unit's
operating mode is checked with the STATUS READ host link command. If the
CPU Unit is found to be in RUN mode, the mode is changed to MONITOR
mode with the STATUS WRITE host link command so that the data can be
written.
When a data write error occurs because the CPU Unit was changed to RUN
mode from a Programming Device, the Simple Communications Unit will
attempt to change the operating mode and write data twice. If these retries
fail, a fatal error will occur and the ERR indicator will light.
The Simple Communications Unit must be switched from Stop to RUN in
order to validate any changes made in Control Data Area words +7 through
+102. After editing these words, always switch the Unit from RUN to Stop and
Section 7-6
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