Delta RMC151 - Manual (Page 473)

6 Communication
1. If you need to write to other variables that are used by the user program (e.g. for
defining speeds, setpoints, etc.), do so first.
2. Write a number to the StartProgram variable. The number will specify which user
program to run.
Handling Broken Connections
Many applications require some type of action if the EtherNet/IP I/O connection breaks
during machine operation. For information on how to handle a broken connection in either
the RMC or PLC, see the Handling Broken EtherNet/IP Connections topic.
Troubleshooting
See the Troubleshooting EtherNet/IP I/O topic.
How the I/O Data is Applied to the RMC
When the Sync register is used, and the RMC sees that the incoming Sync Register
changes, the RMC applies all the data from the PLC to the specified Incoming Cyclic I/O
Data area. When the Sync Register is not used, then when any register changes its value,
then all data is written to the specified Incoming Cyclic I/O Data area.
In certain cases, it may take more than one loop time to apply the data. Therefore, not all
of the data may be valid at the same time. For example, if you are using any of the data
to trigger a user program that also uses some of the data, it is important that the user
program is not triggered before all the data is valid, otherwise, the user program may use
old data.
Data Consistency
When all the incoming data is applied in the same RMC loop time, the data is called
consistent. If the data is consistent, you can use all the data immediately. If the data is
not consistent, you need to make sure that you do not use the data until it has all been
updated.
The following rules apply to data consistency based on where the consuming address is in
the RMC:
Variable Table - Current Values
• For 500 us and longer loop times, all variables will be written at once within a
single motion loop.
• For the 250 us loop time, the first 64 variables will be written on the first
motion loop, and the remaining variables will be written on the next motion
loop. If 64 or fewer variables are written, then all will be written in a single
loop.
Command Area
Writing the data to the Command Area may take up to 3 ms. After the write is
complete, the entire command block is submitted as a single consistent block.
Therefore the data is treated as a single consistent block, although it may take several
loop times before the block is submitted.
Indirect Data Map
The only data guaranteed to be consistent are variables, if they are placed first in the
Incoming Data area of the Indirect Data Map. The size of guaranteed consistent data
depends on the loop time:
• 1 ms or longer loop time: The first 100 registers will be consistent if they are
all variables.
• 500 us loop time: The first 50 registers will be consistent if they are all
variables.
• 250 us loop time: The first 25 registers will be consistent if they are all
variables.
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