An S7-1500 migration from a CPU 315-2 PN/DP: the two migrations, the four message classes in the TIA Portal log, and the STL that comes back marked.
Analogue scaling in STL on an S7-300, S7-400 or S7-1500: multiply before you divide, mind the DINT ceiling, and check OS rather than OV after the chain.
Maximum PROFIBUS segment length at every DP baud rate on type A cable, with repeater rules, termination values and the meter checks that find the fault.
Siemens S7-300 and S7-400 programming: the instruction set, how the bus systems connect, and which communication types each family supports on site.
S7 plc error codes as the CPU reports them: the number, what the text means, and the cause, including calls that break when an interface changed.