DPU Bus Basics, an Introduction
Metso Automation MAX Controls
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277581
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1-5
The optical cable length of each ring must not exceed:
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6600 feet (2 kilometers) between OEIs
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20,000 feet (6 kilometers) circumference
Note:
Each spur can have a maximum total extension of 200 feet with up to
15 stations, so long as the global limits (DPUs/32 stations/10 OEI pairs) are
not exceeded.
Understanding OEIs
Electrical DPU Buses are connected to optical DPU Buses using Model OEI
Optical-Electrical Interface (OEI) devices. These self-contained OEI units
may also be used to extend electrical cables over longer distances and also as
repeaters to extend optical cable lengths beyond 6,600 feet. (nominally 2
km). The Model OEI022 OEI is used with 200 micron fiber optic cable.
Three types of data are passed through the Optical/Electrical Interface (OEI)
of a local electrical DPU Bus.
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Optical data to the fiber optic cable; optical data leaves the optical OEI
emitter.
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Ring data from the fiber optic cable at the OEI; ring data is received by
the optical detector of the OEI.
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Bidirectional electrical data between the OEI and modems of stations on
the local electrical spur.
An OEI functions either as a repeater or as a transmitter when it is connected
to an electrical DPU Bus.
When no stations on the local electrical data spur are transmitting, the OEI
functions as an optical repeater. Optical data appears as both bidirectional
data and ring data on the local electrical DPU Bus. See Figure 1-4. An OEI
can exist on an optical DPU Bus without being connected to an electrical
DPU Bus. In this case, the OEI functions only as a repeater of optical data.
The OEI functions as a transmitter when the control signal is active from a
modem of stations on the local electrical spur of the OEI. Bidirectional data
from the electrical DPU Bus is converted by the OEI to optical data while
ring data is that data received from the optical DPU Bus. See Figure 1-5.
