Hi all!

Recently a PLC had a malfunction and we decided to change it. I uploaded the project some time ago and downloaded it to the new PLC. When it was mounted all was good without any failure, until we connected it to the existent HMI.  The HMI showed "#" on all the input/output fields, just like when there is communication failure. The person in charge of connecting  the new PLC  tested the HMI by  connecting it to another PLC that has the same program the old one had, fit worked great. My question is why is the HMI not working properly with the new PLC ?

The old PLC was a 1214 Ac/DC/Rly and the new one is a 1215 DC/DC/DC. The HMI is a TP1500 Basic Panel. The program has some controls some valves by using buttons on the hmi and it handles 4 modules of outputs and inputs. The version of TIA PORTAL in the previous PLC was V13 and I upgraded it to V14 SP1. The IP's are the same between the three PLC's (the old one, the new one and the one we tested the HMI with). The machines come from other country and nobody has the original program.

When I was testing some functions in TIA PORTAL I found that there are two ways to create a connection between an HMI and a PLC. The first one is by going through the "connections" option in the HMI menu on the left in TIA PORTAL and creating a connection specifying the IP and family of the PLC. The second one is by going to network view and pressing the option connections. This makes a connection between the HMI and PLC but when I go to the "connections" option on the HMI menu the IP of the device cannot be changed.  However,  it does specify the node with the series of the old PLC:"CPU 1215C DC/DC/DC, PROFINET interface (R0/S1)".  My other question is if this configuration has to match with the PLC that was configurated in the  PLC project when it was created?