The two ways that VeriColor products can communicate with either PC's or PLC's (Programmable Logic Controllers) is not fully understood.
Discrete vs RCI Command Communication Methods
Vericolor Discrete Communication -
The VeriColor products have various "Communication Channels" that are designated to perform specific tasks. Separate channels are available to select standards, initiate measurements, report pass, report fail etc. Discrete communications work on the principle that a voltage potential change on any of these channels will "trigger" that channel to perform the specific task on the instrument. VeriColor systems can be configured to be held in either a high voltage or low voltage state. For example, a VeriColor System configured to be held at a high voltage state will be triggered (on a particular channel) if the voltage is cut off on that channel (typically for milliseconds of time). Conversely, if the System is configured to be held at a low voltage state, pulsing a particular channel with voltage potential (again in terms of milliseconds) will "Trigger" the instrument to perform that channels task. Discrete communication is typically used in conjunction with PLC's or controller boards (not PC's).
Typical use- Discrete communication is widely used to allow a PLC to control a VeriColor system in production environments. Typically "Projects", "Standards with tolerances" and "basic operating parameters" are set on the instrument using the VeriColor Software and then after hooking the instrument to the PLC discrete signals are sent from the PLC to "Trigger" the instrument operation. By it's nature discrete communication is less complex than RCI communications.
VeriColor RCI Communication (Remote Command Interface -
Most modern software utilize RCI commands to control instruments. These commands tell the instrument what to do (when the command is sent to the instrument). When you push a button in the software the software (connected to an instrument via RS232 or RS485 nine pin connector to the PC com port) tells the instrument what to do. Any and all functions of the instrument can be controlled via RCI commands (including setting up "Projects","Standards with tolerances" and "basic operating parameters".
Typical Use - RCI commands can be used to "develop custom software" , be programmed into a PLC , or used with a PC running say "Tool Crib" or "Hyper Terminal" to both program and run a VeriColor system. We use RCI commands in our VeriColor product "Troubleshooters" to get projects, clear projects and reset the instrument to factory settings. RCI command manuals for all VeriColor products are available on our website to the general public on the products support page (in the library link).