PLC Generally in an OTS the vendor package logic is simplfied to provide the look and feel of the logic's functionality to the trainee operator at the DCS console. This is because often the vendor doesn't provide the logic and, or because the logic covers areas outside the scope of the OTS, particularly equipment health monitoring or ancillary equipment, or because the detailed operation of the equipment provides little training benefit, for example PSA logic.

For the OTS projects I have worked on, I have mostly emulated the functionality of the vendor logic based on customer provided descriptions or by working through the required functionality with the DCS operator. Although for one project I have implemented the PLC configuration using the emulation support for the controller in the OTS system.

Allen Bradley PC5 1 OTS project. Implementation of PSA logic.
Experienced with Ladder Logic, including implementing the emulation of the complex block functions

Compressor anti-surge (used CCC emulation) 5 OTS projects
Experienced at calculating surge line and controller settings based on model operation

GE Mark V/VI 3 OTS projects
Emulated the logic to control the start-up (including RPM set point signal to Helper motor), load or capacity control, shutdown and trip & emergency stop of the a gas turbine. Simulated to sufficent detail to provide the operator with the look and feel of the system's functionality when operating from the DCS console

Modicon 1 OTS project. Implementation of PSA logic.
Experienced with Ladder Logic

Steam turbine vendor logic 4 OTS projects
Emulated the logic to control the start-up, shutdown and trip & emergency stop of the a steam turbine. Simulated to sufficent detail to provide the operator with the look and feel of the system's functionality when operating from the DCS console, particularly for the start-up sequence including warm-up timers at specified RPM, with warm-up time being a function of casing temperature or time since shutdown, ramp-up rates, ramp rate through critical zone(s), switch to extraction control etc.