TL21 is a part of Miscellaneous Programmable Logic Controllers (PLCS). It is designed to be a cost effective solution for a variety of automation applications such as industrial process control, motion control, and security systems. The TL21 features an 8-bit single-chip microcontroller, 12 general purpose input/outputs, 6 analog inputs, 5 configurable and 4 digital I/O ports, a 12-bit A/D converter, and a 4K bytes of FLASH program memory. It also provides an integrated communications interface, allowing users to connect to various networks, as well as various programming options.