nfthree
Member
We have 5 machines each using a 418-2 CPU. 4 of the lines have automatic bleed off valves to purge gases which might accumulate during production. The fifth line had the bleed off valves, but they were not automatic.
The networks were basically copied from one of the working machines and added to FC3 and the variables for 2 timers and 2 counters were added to DB20 to add the automatic bleeding. Everything was working well until we had a power outage at which point the variables for the timers and counters in DB20 were set to zero, effectively disabling the outputs for the bleed valves.
I have made sure that the initial values for these variables were set offline, saved, and then downloaded to the PLC. Whenever I do a warm boot or recycle power, these values are not set to the initial value though but are set to zero. After a warm boot, I can simply select DB20 from my offline project and download it the PLC which correctly sets the variables to their initial value. I should also note that this DB is a shared one and the only instance of the use of the variable is a read in the added networks.
I've been in contact with Siemens support and they are unable to replicate the issue. They suggest that something is indirectly addressing these variables but I just dont see anything that might be overwriting them.
Has anyone had a similar experience where DB variables were not being retained during a power cycle or warm boot?
The networks were basically copied from one of the working machines and added to FC3 and the variables for 2 timers and 2 counters were added to DB20 to add the automatic bleeding. Everything was working well until we had a power outage at which point the variables for the timers and counters in DB20 were set to zero, effectively disabling the outputs for the bleed valves.
I have made sure that the initial values for these variables were set offline, saved, and then downloaded to the PLC. Whenever I do a warm boot or recycle power, these values are not set to the initial value though but are set to zero. After a warm boot, I can simply select DB20 from my offline project and download it the PLC which correctly sets the variables to their initial value. I should also note that this DB is a shared one and the only instance of the use of the variable is a read in the added networks.
I've been in contact with Siemens support and they are unable to replicate the issue. They suggest that something is indirectly addressing these variables but I just dont see anything that might be overwriting them.
Has anyone had a similar experience where DB variables were not being retained during a power cycle or warm boot?