8
D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – COMMUNICATIONS GUIDE
MODBUS SETTINGS
CHAPTER 2: MODBUS COMMUNICATION
Modbus settings
This section outlines configuration settings from the instruction manual.
Modbus protocol
The Modbus server can simultaneously support one client over serial RS485 and four
clients over Ethernet. The server is capable of reporting any indication or measurement
and operating any output present in the device. A user-configurable input and output map
also is implemented.
The D90
Plus
operates as a Modbus slave device only.
In the EnerVista software, select the
Settings > Communications > Modbus > Protocol
menu to open the Modbus protocol configuration window.
Figure 1: Modbus protocol configuration settings
The following settings are available.
Modbus Slave Address
Range: 1 to 254 in steps of 1
Default: 254
This setting specifies the Modbus slave address for the D90
Plus
. Each device must have a
unique address from 1 to 254. Address 0 and addresses from 248 and up are reserved by
the Modbus protocol specification, and so their use here is not recommended. Address 0
is the broadcast address to which all Modbus slave devices listen. Addresses do not have
to be sequential, but no two devices can have the same address or conflicts resulting in
errors occur. Generally, starting at 1, set each device added to the link to the next higher
address.
Modbus TCP Port Number
Range: 1 to 65535 in steps of 1
Default: 502
Modbus over TCP/IP can also be used on any of the Ethernet ports. This setting specifies
the Modbus TCP port number for Ethernet communications. Power to the D90
Plus
must
be cycled for changes to this setting to take effect.
NOTE
Do not set more than one protocol to the same TCP/UDP port number, as this results in
unreliable operation of those protocols.
Modbus user map
The Modbus user map provides read-only access for up to 256 registers. To obtain a
memory map value, enter the address in the
Parameter
field (this value must be converted
from hexadecimal to decimal format). The corresponding value (if programmed) displays in
the
Value
field. A value of “0” in subsequent register
Address
lines automatically returns
