Luciak Posted April 22, 2011 Report Share Posted April 22, 2011 Simple question - what does system bit SB90 do? It does not have a description in VisiLogic but it is next to SB 91 which is "I/O Exp. Module--Command buffer is full" so based on this and on my tests I think it has something to do with I/O Module too. Why am I interested in this? Well - I have 2 sets as mentioned in Topic description: - the first one is on site and is working hard - the second one is on my desk and I make it suffer As I tested with the one on the desk: - SB90 is "0" when I have I/O module configured in HW configuration, everything is connected correctly and PLC is in run mode. - SB90 is "1" when I have I/O module configured in HW configuration and disconnect I/O module during PLC running or when I have I/O module configured in HW configuration and PLC is starting (eg. after restart) with no I/O module connected Of course when I disconnect I/O module from PLC, every DI and every AI is not read from I/O module by PLC. My concern is that, at the moment, as I read the PLC running on site, SB90 is "1" but I get all the signals from I/O module. I started this tests because I had problem with the PLC on the site - it had just stopped and, as guy working there told my on the phone, You could see Unitronics written on the HMI panel. After restarting PLC (hard way - pluging the power off) everything was ok again. So what does that SB90 really mean? If it is somehow connected with I/O module - it would really help me, if I would have known what way it is connected. Any ideas? Quote Link to comment Share on other sites More sharing options...
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