Modbus Link Alternatives; Serial Link; Modbus Serial Link Parameters - ABB Relion 620 Series Protocol Manual

1MRS757645 B
3.2
3.2.1
3.2.1.1
620 series
Communication Protocol Manual
In PCM600, it is necessary to always define the mappings to be edited or viewed.
Each protocol instance has the setting parameter Mapping selection, which defines the
protocol mappings to be used by this instance. Several protocol instances can use the
same mapping. By default, the Mapping selection parameter for all the instances is set
to use the mapping number one.

Modbus link alternatives

Modbus communication is possible over the serial communication interface, over the
Ethernet interface, or over both interfaces simultaneously.
Depending on the IED type, either only serial communication or only
Ethernet communication may be supported.

Serial link

Modbus serial communication requires that the IED variant is equipped with a serial
interface card at the slot X000. The serial interface card can contain one or two serial
interfaces.
The Modbus link mode can be either Modbus RTU or Modbus ASCII.
Modbus serial communication can run on two separate serial ports simultaneously.
The Modbus serial link characteristics can be different on the two ports. This applies
also to the Modbus RTU and ASCII link modes and the unit address.
Documentation concerning the Modbus serial link messages and the
Modbus standard can be obtained from www.modbus.org.

Modbus serial link parameters

Serial link setting parameters can be accessed with Parameter Setting tool in PCM600,
WHMI or via the LHMI path Configuration/Communication/Modbus.
Address
Each serial link can be given a separate unit address.
End delay
The end of message delay, or timeout, is used only in the Modbus RTU link mode.
According to the Modbus standard, an idle period of 3.5 characters, that is the time it
takes to transmit 3.5 characters with the used baud rate, defines the end of a Modbus
Vendor-specific implementation
Section 3
15