Further Hot
Standby setup
I you intend to use a controller that has had program downloaded, a recommended
practice will be to adopt the same kind of progression than the one previously
described, in order to succeed in the setup of this Hot Standby system, i.e. one
controller at a time.
So, power down one of the units, in order to work at first on a unique one. We
suggest you work with the controller having the lower MAC address: it acts as
Controller A, initially standing as the Primary unit. A download operation should
normally place this unit into a Primary state. Power up the second unit. Depending
on the current contents of this 'to-be-Standby' unit, a transfer may automatically
occur. If not, it may be necessary to manually ask for this transfer to occur. A safe
practice would be to systematically execute a transfer from Primary to Standby,
downloading a newer project.
In that latter case, the transfer has to be asked for from the Primary's keypad. ("PLC
Operations" => "Hot Standby" => "Transfer" => Enter)
Note: Verifying
If you fail to establish a connection, first check the cable, but also, use the
keypad to check the parameters governing this port. If required, feel free to
modify these parameters according to your needs.
Once having done an important operation on a CPU, such as a project
download, it's a good practice to verify with the keypad if the operated machine
has now got its expected state. For example, a quick check will verify either on
supposed-to-be-primary, and respectively on supposed-to-be-standby, the
respective Modbus Plus Port address.
