“How does SoftPLC communicate to I/O?"
SoftPLC works with a wide variety of I/O systems. Typically, a hardware I/O interface card is used to facilitate communications between SoftPLC's software I/O driver and the I/O system and modules. The hardware required is available from the I/O vendor(s) or their distributors. SoftPLC Corporation also distributes some of the more popular I/O interface cards, as well as providing their own SoftPLC In Tealware I/O system.
Some I/O cards fit directly into the SoftPLC computer chassis, in which case the I/O driver talks to the I/O over a PC bus or backplane through memory. Examples of this type include PC/104 I/O from Sensoray, Diamond Systems and ComputerBoards.
Some I/O communicates to the SoftPLC driver through standard ports, such as serial or parallel ports in the SoftPLC computer. One example of this type is Advantech's ADAM I/O.
Most customers use remote I/O or fieldbus I/O systems which typically utilize an I/O scanner or interface card that fits into the SoftPLC computer. In these cases, the SoftPLC I/O driver communicates to RAM memory on the card, which handles the communication to/from the actual I/O modules. Examples of this type include Profibus, DeviceNet, or A-B Remote I/O.