800xa communication variables
the communication works partially, some variables appears with time out error, I changed time interval to: slow to all variables and communication works fine.
my question is: Is there any limitation of number of variables than can be configured as communication variables?
and why it was necesary for me in this case to change interval time to slow option?
What version of 800xA / AC800M Connect are you using?
There are some known issues with IAC in older versions that could lead to timeouts, i guess your case could be Field Alert 3BSE047421D0189
AC 800M Controller Firmware, Version 5.1.0-x, 5.1.1-1 to 5.1.1-3 and 6.0.0-0, IAC
Communication might be Disturbed after Cold or Init Application Download to IAC Client
-> only workaround in that case is to restart (reset) the controller again and check number of connections (IAC Diagnostics Dialog) are correct.
Theres a limit on the number of messages and on the size of each message. Practically speaking each message should be less than 1 k.
60 real variables fit easily into a single message ( all in the same MMS_Read block or same scan interval / source / target for IAC. ) This is no problem at all for MMS
Using 60 messasges - 1 for each variable - could be an issue depending on comms load on the controllers and the scan rates used. Theres a formula on this site somewhere.