Differences between Siemens and other PLCs
Languages in Siemens closely relate to those of other major platforms. Ladder, FBD, SCL (or ST in most other environments), and STL are all ultimately the same. The other languages are either unique to Siemens or have noticeable variations compared to other environments. Despite the most common languages being the same for the most part, there are a few things to watch out for that are subtle and not immediately obvious.
Timers
In TIA Portal, when an IEC timer is used (TON
, for example), everything appears normal compared to other IEC environments.
However, if the PT
value is changed while the IN
input is True
, Timer
does not respond to the change until the IN
input has become False
and then True
again. This is not immediately obvious and is not the expected behavior compared to other environments.
TIA Portal has a solution to this, which is to place a PT Coil
before...