Rockwell Automation 1768-EWEB EtherNet/IP Web Server Module User Manual - Manual (Page 136)

Publication ENET-UM527E-EN-P - October 2006
136 Socket Interface
situation, your (old) MSG instructions may succeed but may not be
communicating with the correct remote device.
Handle this situation by monitoring the status of the web server via a
GSV instruction. If you lose communication with the web server, the
Logix5000 program should re-initialize its socket communications.
For more information on the GSV instruction, see the Logix5000
Controllers Common Procedures Programming Manual publication
number 1756-PM001.
Change Controller Mode Between Run and Program
If the Logix controller transitions from Run to Program mode while
socket requests are active, the transition does not complete until all
the outstanding MSG requests complete or time out. If you have long
timeout values, you can experience an unexpectedly long time for the
Run-to-Program transition to complete.
Alleviate long transition times by appropriately setting the Timeout
parameter for the socket services. In the Logix5000 program, you can
also set the .TO bit for any outstanding socket-related MSG
instruction. This causes the MSG instruction to timeout and set the .ER
bit.
If the controller transitions from Run mode to Program mode, then
back to Run mode again, previous socket instances may still exist on
the web server. The previous socket instances time out eventually.
Depending on the number of sockets you need, your program may
encounter errors during Run-Program-Run transitions because all of
the available socket instances are in use. To alleviate this situation:
1. Wait for all socket instances to time out before putting the
controller in Run mode.
2. When the Logix5000 program starts, use the DeleteAllSockets
service to delete any previous instances.
The DeleteAllSockets service deletes ALL socket instances, not just
those created by the controller calling the service.