GE GEH6505A manual Modbus Connection Diagnostic Connection, Wiring Rules Modbus Networks

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POWER LEADER™ Ethernet Gateway

Chapter 2 – Installation

2–4 Modbus Connection

2–5 Diagnostic Connection

The Modbus RTU networks should be connected to the RS485 ports on the back of the Ethernet Gateway, as shown in Figure 9.

The RS232 port on the back of the Ethernet Gateway is provided for connection of a dumb terminal to the Gateway. The terminal may be used for configuring the Ethernet Gateway’s settings or for diagnostic purposes. For diagnostic purposes, the Gateway may be set to display all messages and traffic on the terminal so that problems may be tracked down and corrected. To connect a terminal (usually a laptop computer running Windows’ Terminal accessory software) to the Gateway, plug its RS232 cable into the RS232 port on the back of the Ethernet Gateway, as shown in Figure 11.

Figure 9. Connecting an RS485 network to the Ethernet

Gateway.

Per the EIA-485 standard, the RS485 networks must be terminated at both ends. Position the Ethernet Gateway at one end of the RS485 networks, as it is internally terminated. The user must ensure that the final device on each network is terminated correctly, as shown in Figure 10.

Figure 11. Connecting a dumb terminal to the RS232 port.

2–6 Wiring Rules – Modbus Networks

Figure 10. Terminating an RS485 network at the last device.

When wiring Modbus RTU devices to an Ethernet Gateway, follow the wiring rules below to ensure proper configuration. Refer to GEH-6502, the PMCS Network Architecture Guide, for specific examples of correct and incorrect configurations.

1.Up to 31 Modbus devices may be attached to a single Modbus network. RS485 repeaters do not have Modbus addresses, but do count as devices toward the 31 physical devices per network limit.

2.Every device on a single Modbus network must have a unique address. (Devices on different networks may use the same Modbus address, i.e., it is acceptable to have a device addressed as device 10 on Network 1 and another device addressed as device 10 on Network 2.) Use the Modbus address worksheets (at the end of this

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Contents Power Leader Ethernet Gateway User’s GuideAS Used in this Publication Table of Contents Table of Contents Introduction Introduction OverviewPhysical Description HDDOperational Description Message FormatSpecifications Terminology Environmental RequirementsControl Power Connections InstallationInstallation Mounting Ethernet ConnectionModbus Connection Diagnostic Connection Wiring Rules Modbus NetworksPower Leader EPM Modbus Equivalent AddressesConfiguration ConfigurationConfiguration Procedure Baud Rate Specification Ethernet Gateway IP AddressMessage Monitoring Ethernet DriverGateway Diagnostics Display Socket, IP Address and Subnet MaskAdvanced Options Technical Support Personnel only Network Test Factory USE onlyOperation OperationErrors and Diagnostic Messages Diagnostic Messages and Errors Monitor ModeTroubleshooting Guide Troubleshooting GuideConfiguration Worksheets RS485 Port Configuration WorksheetsRS485 Port 2 Worksheet Baud Rate for RS485 Port RS485 Port 3 Worksheet Baud Rate for RS485 Port RS485 Port 4 Worksheet Baud Rate for RS485 Port GE Electrical Distribution & Control
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