N°98.60.17.013.0
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080424/1
2.1 Communication
The LEM proprietary communication bus is generally referred to as S-Bus or I-Bus, dedicated
link for I-Link modules. In practice, both have exactly same characteristics and function in the
same way.
Based on serial full duplex communication, each device has an unique ID, 001-254, which
identifies it on the appropriate bus.
The link is a 4-wires one (Rx, Tx, 2xGnd) and is able to support 125 devices with correct
network performance.
The transmission speed is 9600 baud, with no flow control and following data frame:
Start bits: 1
Stop bits: 1
Data bits: 8
Parity:
None
The electrical interface is custom designed. For this reason, it is not possible to directly
connect Sentinel or I-Link device to the OCS. A LEM-supplied Bus Converter module is
needed; it is in charge of generating the correct signal levels (note: no software protocol
translation is performed).
The device is instructed by means of a command set addressed to the unit and provides data and status
information in the form of a response set. It never analyzes the measured parameter by itself. It doesn’t
make an unsolicited or spontaneous transmission to the network.
The only exception is a “READY”
announcement following a successful start-up (detailed in 3.2)