mistic I/O and Control Systems

The first complete Opto 22 hardware and software system to offer full industrial control, mistic control systems are still in use worldwide.

Mistic control systems today use powerful controllers like the SNAP-LCM4 and Opto 22's FactoryFloor, an integrated suite of industrial control software applications designed to help you solve control automation problems, build easy-to-use operator interfaces, and expand your manufacturing systems' connectivity.

The controllers run OptoControl flowchart-based control strategies and connect to I/O units for distributed control. Each I/O unit consists of an I/O processor (usually called a brain) and I/O modules on a mounting rack. Depending on the controller and brain you choose, you can use G1, G4, or SNAP analog, digital, or special-purpose modules.

Most mistic control systems run on serial networks. For ARCNET networks, choose an ARCNET brain and add an ARCNET adapter card for the controller. A mistic control system can also run on a wired Ethernet network using the M4SENET-100 controller adapter card and a SNAP Ethernet brain.

mistic I/O

Opto 22's mistic protocol I/O units are a family of intelligent digital and analog input/output units that operate as slave devices to a host computer. Physically, each Mistic I/O unit is a modular assembly that consists of a module mounting rack, a brain board, and a number of optically-isolated analog or digital I/O modules.

Brain Board

The removable brain board contains a microprocessor that communicates with a host computer equipped with the proper interface card. The brain board controls the plug-in I/O modules located on the I/O mounting rack.

I/O Units and Modules

Any combination of analog I/O modules may be plugged into an analog I/O unit and likewise, any combination of digital I/O modules may be plugged into a digital I/O unit. Remote analog and digital I/O units can then be combined on the same RS-485 serial data link providing endless combinations of analog and digital I/O points. In a similar way, any combination of local analog and digital I/O units can be combined on the same parallel data link.

Local analog and digital I/O units use flat ribbon cable for interconnections. The maximum cable length for local I/O units is 200 feet. Local units should be used within the same equipment rack or enclosure where cable runs can be kept short. The primary reason for choosing local I/O units (rather than remote) is the much higher bus speed of 1.4 MHz. The remote bus speed is 115 kHz. The higher speed of the local I/O unit allows data to be sent and received in a much shorter time interval. This is very important for real-time control applications.

Communications

Remote I/O units communicate with the host computer over an RS-485 serial communications link. The serial data link is composed of two twisted-pairs of cable (4 wires) that connect to each I/O unit. One pair carries commands and responses and the other pair is used for a hardware interrupt from the I/O units. It is possible to communicate with up to 256 individual I/O units on a single serial link for a total of 4,096 digital and analog I/O points.

The RS-485 data link offers excellent noise immunity and long cable lengths. The maximum cable length for remote I/O units is 3,000 feet. Wiring costs are reduced by eliminating the need for bringing large bundles of field wiring back to a central controller. Remote I/O units can be located where the actual control is needed.