Whether it is PLC project development, or later maintenance, there is a small problem, the equipment will not act for no reason, the general experienced PLC engineers will write the alarm in detail, but there is still inevitable negligence.
At this time, how should we remedy, next, I will introduce you to a very interesting application, you can display the PLC process on the HMI, as long as the device stops, you can show in real time in the HMI where to stop, what this step is to do, what conditions are needed! The debugging personnel can spend a lot less time to connect the machine, and some personnel who are not skilled in using PLC can also make a simple judgment. The following is the implementation steps for your reference.
1) First of all, create a FB block of Graph process, use the FB block to program the flow chart, open the FB function block, and check "Display/access internal parameters from HMI" in the edit menu, as shown in the following figure:
2) Create a new screen in HMI and add a control "GRAPH overview", as shown below:
2. Add a "Screen 4", and add a control "PLC code view" in it, as shown below:

3. Configure the control and connect the variable to "OFF_SQ" in the background block of the corresponding FB block, as shown in the following figure:
4. Edit the "PLC code View button click" in the event, so that when you press the button when there is a problem, you can jump out of the corresponding "picture 4" directly, and display the corresponding PLC code in the picture 4, as shown below: 5. The execution result is shown in the following figure. Stop at the second step because the M20.0 signal is not satisfied, as shown in the following figure:

6. Well, this is just a simple example, PLC engineers need to consider the variable name, the name of the step number when programming, so as to achieve the ideal effect.