Arian instruments send continuouslly data (e.g. temperatures, counts, positions of valves) to a PC by means of a single wire pair across the plant.
Having in the PC a continuous historical data registry makes possible to generate automatically production reports.
Derived benefits will be improvements in the productivity, cost reduction and a superior quality control.

Each instrument haves the optional RS485 isolated output card installed.
The RS485 bus is a low cost twisted single wire pair that connects the devices thru the plant and ends in the ISO485 interface module that converts RS485 in to galvanically isolated RS232.
Finally the RS232 connects to a PC serial communications port.

By other side, from the software point of view, the instruments use the Modbus RTU protocol for exchanging data with the PC thru the RS485 bus.
On the PC must be running the Arian Opc V4 server software making it the Modbus arbiter that collects data from the instruments (slaves).
Data is displayed on the software console, stored as text files (for later processing) and presented in OPC format to other applications executed on the same PC or in the Net.
Such applications are typically HMI/MMI (Human Machine Interfaces / Man Machine Interfaces) software packages for displaying information in a friendly way.
OPC is a client-server based architecture for enabling communication between two applications running on distributed computers.
The OPC Data Access Specification utilizes DCOM for communication between the OPC Client ( eg. An HMI application) and the OPC server.

- Each of the devices must have installed RS485 comunications option.
- One ISO485 interface device for isolating and controlling the RS485 bus from the PC com port
- The Arian Opc Server software (free download)

- Galvanic isolation of instruments from the bus and from the bus to the PC.
- RS485 Half duplex (1 pair). Modbus RTU software protocol.
- Maximum bus length is 1200 meters. Using a twisted pair AWG # 24.
Digital communications by means of RS485 serial bus was conceived specially for industrial environments where noise and interference immunity is required.
The scheme of distributed control and centralized supervision universally is accepted as the most reliable. When a device fails, the rest continue operating independantly.
The Arian OPC V4 Software is executed on a PC compatible computer with windows W95, W98, W2000, XP operating system.
It will arbiter the Modbus RTU bus on serial ports comm1 to comm4 and return data as a OPC server under DA2 specification.