GE L90 Instruction Manual page 216

PRODUCT SETUP CHAPTER 5: SETTINGS
upgrade the relay firmware. A maximum of 32 relays can be daisy-chained and connected to a DCS, PLC, or computer
using the RS485 ports. If IEC 60870-103 is chosen as the protocol, valid baud rates are 9600 and 19200 bit/s, and valid
parity is Even.
— This setting specifies the minimum time before the rear RS485 port transmits after
RS485 COM2 RESPONSE MIN TIME
receiving data from a host. This feature allows operation with hosts that hold the RS485 transmitter active for some time
after each transmission.
5.3.4.3 Ethernet network topology
The L90 has three Ethernet ports. Each Ethernet port must belong to a different network or subnetwork. Configure the IP
address and subnet to ensure that each port meets this requirement. Two subnets are different when the bitwise AND
operation performed between their respective IP address and mask produces a different result. Communication becomes
unpredictable when more than one port is configured to the same subnet.
Example 1
IP1/Mask1: 10.1.1.2/255.255.255.0 (where LAN 1 is 10.1.1.x/255.255.255.0)
IP2/Mask2: 10.2.1.2/255.255.255.0 (where LAN2 is 10.2.1.x/255.255.255.0)
IP3/Mask3: 10.3.1.2/255.255.255.0 (where LAN3 is 10.3.1.x/255.255.255.0)
Example 2
IP1/Mask1: 10.1.1.2/255.0.0.0 (where LAN1 is 10.x.x.x/255.0.0.0)
IP2/Mask2: 11.1.1.2/255.0.0.0 (where LAN2 is 11.x.x.x/255.0.0.0)
IP3/Mask3: 12.1.1.2/255.0.0.0 (where LAN3 is 12.x.x.x/255.0.0.0)
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Example 3 — Incorrect
IP1/Mask1: 10.1.1.2/255.0.0.0
IP2/Mask2: 10.2.1.2/255.0.0.0
IP3/Mask3: 10.3.1.2/255.0.0.0
This example is incorrect because the mask of 255.0.0.0 used for the three IP addresses makes them belong to the same
network of 10.x.x.x.
Single LAN, no redundancy
The topology shown in the following figure allows communications to SCADA, local configuration/monitoring through
EnerVista, and access to the public network shared on the same LAN. No redundancy is provided.
5-30 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL