Operation during the simple CPU communication
■Operation of the own station
Since the own station operates without depending on the operating status of the CPU module, the simple CPU
communication is performed even when the CPU module is in the STOP state because of stop error. When an initial
communication error occurs, communications of the corresponding setting numbers are stopped and ones of the setting
numbers, where no error occurs will operate.
If the communication destination responds at the timing of the END processing of the CPU module, data is transferred to the
system area for the simple CPU communication. For devices other than the SLMP-compatible device (QnA-compatible 3E
frame), data inconsistency will not occur in one setting since processing is executed by one setting unit.
■Operation of the communication destination
The operation differs depending on the communication destination.
MELSEC iQ-R (built-in Ethernet)
MELSEC iQ-F (built-in Ethernet)
MELSEC-Q (built-in Ethernet)
MELSEC-L (built-in Ethernet)
SLMP-compatible device (QnA-compatible 3E
*1 The order of the read and write is shown below.
When "Write" is set for the communication pattern: A word device comes first, then a bit device.
When "Read" is set for the communication pattern: A bit device comes first, then a word device.
Communication Time-out Period/Communication Retry Count/Monitoring Time At Error
When the communication destination does not respond or returns an error response, the communication will be retried
(resent) after the time-out period has passed.
At this time, after communications are performed for the communication retry count + 1 times, the fixed interval
communication is performed during the monitoring time at error. If the communication destination responds after these
communications, the communications at the execution interval specified with the parameters are restarted.
Error detection timing when 2 is set for the communication retry count
The error is detected if the communication destination does not respond or communications fail by when the
following time has passed: (communication retry count + 1) communication time-out period
Data operation in one setting
Since the data in one setting is communicated at the same timing, data inconsistency will not occur.
The data specified with a bit device or a word device in one setting is communicated at the same timing.
However, if both a bit device and a word device are set for the same setting number, the data of each
device may be communicated at different timing.
error at the
error at the
1.14 Simple CPU Communication Function (CPU Module (Built-in Ethernet Port Part))
error at the