Serial port connection to PLCs
Programmable Logic Controllers (PLCs) are a specialized variety of computer typically used for controlling machinery on assembly lines and other systems needing mechanical and electrical robustness. They provide industrial-grade levels of immunity to electrical noise, precisely deterministic timing, and the ability to operate in a wide range of temperatures.
They are intended to provide numerous inputs and outputs and are used to replace older systems of relays. switches, and timers. One major advantage of PLCs is the flexibility they introduce into systems that were previously hard-wired.
This flexibility comes from the programmable nature of of PLCs, as their name indicates. But unlike computers most people are familiar with, PLCs lack the usual human-based keyboard/monitor/mouse interfaces of conventional systems. Instead, they are programmed by receiving downloaded instructions that have been generated on a separate computer with the intention of being “injected” into the PLC. The usual interfaces for downloading PLC programming are Ethernet, RS-232, RS-422, and RS-485.
LAVA Ether-Serial Links can provide network-enabling to serial-based PLCs with no built-in networking capability, or supply a serial port interface to computers lacking serial ports. LAVA RS-232 and RS-422 boards for PCI and PCIe are also suited to PLC programming.