Antx DiaLog Elite, Manual

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DiaLog Elite PLC Interface Manual
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What is the Modbus Master Interface Option?
The Modbus Master Interface enables the DiaLog Elite to read input values from a PLC or
Modbus Slave device and write relay control values to a PLC or Modbus Slave device.
The connection uses the RS-232 serial connector on the Elite. The protocol is Modbus
RTU, where the Elite is the Master and the PLC or Modbus I/O is the Slave.
The option supports a combination of up to 72 total I/O channels – up to 48 of which can
be physical I/O in the Elite.
The I/O in the Modbus Slave can be any combination of analog (holding registers) or
digital points (coils).
Values that are read from the Modbus Slave are interpreted by the Elite the same as if they
were physical I/O in the Elite. All the alarm and control logic within the Elite operate on
data coming from Modbus registers.
The communications link between the Elite and the PLC is monitored several times a
second. If the communications link stops functioning after repeated attempts, a
Communications Channel (06) alarm is initiated. This alarm is treated exactly like any
other system alarm allowing the system to call out, drive local relay or issue reports.
The Modbus Master option does not require the Modbus RTU Option in the Elite, but both
can be installed. When both are installed, the Elite acts as a Modbus Master to the PLC
and a Modbus Slave to your SCADA software or to another Elite.
©
Antx, inc. 2001 Version 1.2
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