User`s guide

Data Menu 21
No access 0004
Bad, Configuration Error.
Data communications are good. Data cannot be sent
and/or received.
Cannot access the item.
The item does not exist.
The item is not available.
The server is able to communicate with the PLC but is not
able to access the register.
The server determined the point is not valid.
The PLC responds that the register does not exist, cannot
be read, or cannot be written.
Cannot access a fenced, write-protected, or read-only item.
The PLC is in a mode which does not permit access to this
item.
Incorrect number of data bytes (but the message is
otherwise good).
Invalid command or invalid op code (but the message is
otherwise good).
The PLC is busy. The server gave up retrying.
No communication 0018
Data communications are down.
Cannot access the PLC due to a communications error.
The topic is in slow poll (or equivalent) mode.
The PLC does not exist and/or is not responding.
There is no link validating message.
Lack or resources in the server. A TSR (or driver) cannot
allocate memory.
Lack of resources in the communications link.
The communications link is off-line.
All communications channels are in use.
The network is unable to route the message to the PLC.