GE GEH6505A manual Modbus Equivalent Addresses, Power Leader EPM

POWER LEADER™ Ethernet Gateway

Chapter 2 – Installation

manual) to record the devices attached to each network and verify that each device on each network has a unique address.

3.Modbus Concentrators may be used to add

POWER LEADER commnet devices to a Modbus network. The Concentrator assigns a Modbus-equivalent address to each commnet device attached to it. See Section 2-7 for a discussion of commnet and Modbus-equivalent addresses.

NOTE: While Modbus Concentrators are counted as regular Modbus devices, the commnet devices attached to Modbus Concentrators do NOT count toward the 31 device/network limit, but ARE considered in the 247 address/network limit.

4.No connections between Modbus networks are permitted, either directly or through repeaters.

5.Modbus networks are constrained to a maximum 4,000 feet of communication cable without repeaters.

6.RS485 repeaters may be used to extend the wiring length of a Modbus network or to provide isolation between runs of cable in a

Modbus network. Refer to GEH-6502 for appropriate wiring lengths with repeaters.

2–7 Modbus Equivalent Addresses

A maximum of 31 Modbus devices can be supported on a single RS485 network of the Ethernet Gateway. However, the Modbus RTU protocol permits up to 247 individual addresses to be recognized. These additional 216 addresses may be utilized by commnet devices attached to a special Modbus device, the Modbus Concentrator.

Commnet is a communications protocol utilized by many of the devices from GE’s POWER LEADER family of power management devices. The Modbus Concentrator is a Modbus RTU device that permits commnet devices to be assigned Modbus-equivalent addresses. Each Modbus Concentrator keeps track of up to 32 commnet devices and directs traffic between the Modbus network and the commnet

devices. To the Modbus network, the commnet devices appear as valid Modbus addresses.

To provide seamless integration of commnet- compatible devices into the Modbus RTU network, the Concentrator directly maps commnet addresses to equivalent Modbus addresses. The valid range of commnet addresses recognized by the concentrator is 300–514. These addresses are one-to-one mapped to the equivalent Modbus address range of 33–247.

For a more detailed discussion of commnet devices and the function of the Modbus Concentrator, see GEH-6491, the Modbus Concentrator Users Guide.

Table 4 lists commnet devices supported by the Modbus Concentrator (and the Ethernet Gateway).

Device	Description
POWER LEADER EPM	Full-function, three-phase electronic
	meter with optional pulse initiation;
	simple retrofit to existing
	electromechanical installations. See
	GEH–6302 for a full description.
POWER LEADER Meter	Full-function three-phase meter with
	optional protective relaying and
	waveform capture. See GEH–5892.
POWER LEADER MDP	Three-phase and ground protection
Overcurrent Relay	against overloads and rapid
	detection of short circuits.
	See GEK–100682.
Spectra ECM™	Advanced motor protection in full-
	voltage-nonreversing (FVNR) and
	full-voltage-reversing (FVR)
	combination starter applications.
	See GEH–6435.
MicroVersaTrip PM™ trip	Overcurrent protection and optional
unit in Spectra RMS™	full-function metering and protective
molded-case circuit	relaying. See GEH–5934.
breakers
MicroVersaTrip PM™ trip	Overcurrent protection and optional
unit in AKR, Power	full-function metering and protective
Break® and Power	relaying. See GEH–6273.
Break® II insulated-case
circuit breakers.

Table 4. POWER LEADER commnet devices supported by the

Modbus Concentrator.

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