Modbus - GE 350-A9 Instruction Manual

S1 RELAY SETUP

Modbus

6–14
LLA PRIORITY
Range: Enabled, Disabled
Default: Enabled
This setting is only used when REDUNDANCY is set to LLA.
If this setting is set to ENABLED, Port A has priority. If the Port A LLA detects a problem
with the link, communication is switched to Port B.
If this setting is set to DISABLED, there is no priority, and therefore there is no primary
port. Communications switch to the other port whenever the link fails.
With LLA enabled, the primary port is Port A while the secondary (redundant) port is Port
B. Ports A and B use the Port A MAC and IP address settings, with Port B in standby mode
such that it does not actively communicate on the Ethernet network but does monitor
the link. If a problem is detected with the Port A link, communications switch to Port B
temporarily. Once the Port A link has been regained and monitored for the duration of
the LLA TIMEOUT, communications automatically switch back to Port A, the primary
port.
LLA TIMEOUT
Range: 0 to 65535 s in steps of 1 s
Default: 300 s
This setting is only used when REDUNDANCY is set to LLA and LLA PRIORITY is set to
ENABLED. When the link on the primary port is detected after it fails, the LLA TIMEOUT
setting is the network health monitoring time. During this time, the secondary port
remains active.
If primary network remains healthy for the duration of the LLA TIMEOUT value,
communications switch back to the primary port automatically.
The Modicon Modbus protocol is supported by the 350 . Modbus is available via the RS485
serial link (Modbus RTU). The 350 always acts as a slave device, meaning that it never
initiates communications; it only listens and responds to requests issued by a master
device. A subset of the Modbus protocol format is supported that allows extensive
monitoring, programming, and control functions using read and write register commands.
Refer to the 3 Series Communications Guide for additional details on the Modbus protocol
and the Modbus memory map.
The Modbus server can simultaneously support two clients over serial RS485. 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 is also implemented.
The 350 operates as a Modbus slave device only
Select the Settings > Communications > Modbus > Protocol menu item in EnerVista
3 Series Setup software, or the
path to set up the modbus protocol as shown below.
MODBUS PROTOCOL
Figure 6-5: Modbus protocol configuration settings
The following Modbus settings are available:
SETPOINTS > S1 RELAY SETUP > COMMUNICATIONS >
350 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS