Hi again GIT.
I see that you have 32-point i/o cards.
I dont particularly like the 32-point cards with S7-300, but in order to line up the new cards with where the old was, you may have to use 32-point cards.
There should be a special 40-pin connector for 32-point cards that have more space than the normal 40-pin connector.
As for the CPU, you may find it overkill, but I firmly believe that any new machine, except for the simplest and smallest ones, shall have ethernet onboard. I recommend a 315-2PNDP as the minimum, as you get both Profibus and Ethernet with this one.
Anyway, my best tips are regarding if you have to make the switch in the shortest possible time. Like shutdown the old S5 machine friday evening, start again monday morning with a new S7.
Investigate all sensors and actuators.
It is important that you get things like NO. or NC. correct the first time. And also check directions of valves, motors etc.
Dont trust the old documentation !
Investigate the wiring to the i/o. It makes a huge difference if you can reuse the wiring or not.
If there is enough slack in the wiring or the new i/o can sit in exactly the same position as the old i/o, then proceed with checking the old i/o adressing scheme, and if there are wire numbers on all wires. The numbering should follow the i/o adresses, not the terminal numbers (because the terminal numbers may change). Common wires should be labelled "GND" and "24V+" or something like this.
Then configure your new S7 PLC with the i/o that best macthes the old i/o.
Select the new i/o to have exactly the same addresses as the old.
Prepare diagrams and wiring lists with new PLC hardware.
Be particularly careful with a wiring list that details what i/o wire goes to which module and terminal on that module.
Then it is time to make the PLC and HMI programs.
Because all i/o is well defined, you will avoid making all the small mistakes for example of opening in stead of closing because a valve or sensor worked the opposite as expected.
With S7 and WinCC Flexible, you can simulate your programs as if they were running for real. This is an invaluable help. (from OP/TP177B and up you can simulate the HMIs).
PLCSIM costs approx 400 Euro. If this is too much for you, then simply purchase the PLC and HMI hardware so well in advance, that you can use it as a free simulater for the finished project.
You have to make special simulation code in your S7 program. The code shall manipulate the inputs, depending on what the outputs do. I can simulate up to 95% of the functionality in my programs.
When D-day comes you proceed as follows:.
Remove all S5 hardware,
but leave the i/o wiring in the old S5 i/o connectors.
Install the new S7 hardware.
Now connect the i/o wiring by taking wires one-by-one from the old connectors and place them in the new connectors. The wiring list and the wire numbers shall help in that this goes really fast.
When finished, power up.
Make an i/o test of all i/o signals.
When OK, start the PLC program, and start testing the running functionality. Because you have simulated the program already, it will go really fast too.
Hope this helps.
Let us hear how it goes.
