Do you require a large quantity of temperature controls? Do you need a compact grouping of these controls? If so, consider a multi-loop control system, which can easily integrate into the PLC control.
A multi-loop control system allows for full integration of the temperature control system to be used within a machine. It allows for higher scan speed within the PLC, by not requiring the PID loops to be run within the PLC. It also allows a user to use their existing HMI touchscreens and external controls run by the PLC.
There are many combinations of control loops, output types, FM limits, heater diagnostics, and communication protocols to choose from.
See related feature article, "Use a PLC or Stand-Alone Temperature Control?"