Debugging; General Communications; Ethernet/Ip Communications; Ethercat Communications - Omron NJ501-1 Series User Manual

Debugging

• Forced refreshing ignores the results of user program execution and refreshes I/O with the specified
values. If forced refreshing is used for inputs for which I/O refreshing is not supported, the inputs will
first take the specified values, but they will then be overwritten by the user program. This operation
differs from the force-set/reset functionality of the CJ-series PLCs.
• You cannot upload or download information for forced refreshing with the Sysmac Studio.
After downloading data that contains forced refreshing, change to RUN mode and then use the Sys-
mac Studio to perform the operation for forced refreshing.
Depending on the difference in the forced status, the control system may operate unexpectedly.
• Do not specify the same address for the AT specification for more than one variable.
Doing so would allow the same entity to be accessed with different variable names, which would
make the user program more difficult to understand and possibly cause programming mistakes.

General Communications

• When you use data link communications, check the error information that is given in _ErrSta (Control-
ler Error Status) to make sure that no error has occurred in the source device. Create a user program
that uses reception data only when there is no error in the source device. If there is an error in the
source device, the data for the data link may contain incorrect values.
• Unexpected operation may result if inappropriate data link tables are set. Even if appropriate data link
tables have been set, confirm that the controlled system will not be adversely affected before you
transfer the data link tables. The data links start automatically after the data link tables are trans-
ferred.
• All CPU Bus Units are restarted when routing tables are transferred from Support Software to the
CPU Unit. Confirm that the system will not be adversely affected by restarting before you transfer the
routing tables.
• Tag data links will stop between related nodes while tag data link parameters are transferred during
Controller operation. Confirm that the system will not be adversely affected before you transfer the
tag data link parameters.

EtherNet/IP Communications

• All related EtherNet/IP nodes are reset when you transfer settings for the built-in EtherNet/IP port
(including IP addresses and tag data links settings). Confirm that the system will not be adversely
affected by resetting nodes before you transfer the settings.
• If EtherNet/IP tag data links (cyclic communications) are used with a repeating hub, the communica-
tions load on the network will increase. This will increase collisions and may prevent stable communi-
cations. Do not use repeating hubs on networks where tag data links are used. Use an Ethernet
switch instead.

EtherCAT Communications

• Make sure that the communications distance, number of nodes connected, and method of connection
for EtherCAT are within specifications.
Do not connect EtherCAT communications to EtherNet/IP, a standard in-house LAN, or other net-
works. An overload may cause the network to fail or malfunction.
• Malfunctions or unexpected operation may occur for some combinations of EtherCAT revisions of the
master and slaves. If you disable the revision check in the network settings, use the Sysmac Studio to
check the slave revision settings in the master and the actual slave revisions, and then make sure
that functionality is compatible in the slave manuals or other references. You can check the actual
slave revisions from the Sysmac Studio or on slave nameplates.
NJ-series CPU Unit Hardware User's Manual (W500)
Precautions for Safe Use
21