User`s manual

Western Reserve Controls 1782-JDM User’s Manual
PUB 24.0
2
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Operates independently of operation of Modbus device
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Forwards the message received without interpretation
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Each JDM communicates with one or more Modbus devices
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ODVA Conformance tested to DeviceNet Spec 2.0
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DeviceNet Autobaud operation
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Polled I/O
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Explicit Messaging
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All Modbus registers on target device are accessible
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Upgrades to the Modbus device do not require updates to the JDM
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Software Configurable Parameters for device operation
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Address selection via DIP switches
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DIN rail mount
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Pluggable 5-pin DeviceNet connection
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Pluggable RS232/RS485 3-pin connection
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Choice of RS232, RS485 or isolated RS232 serial interface
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Standard DeviceNet module and network status LED’s
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Serial port transmit and receive LED’s
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Powered from DeviceNet network
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Optional isolated RS485 interface
1.2 DeviceNet System Architecture
A DeviceNet network is a distributed I/O system that may contain many different products from several
different vendors. Products may be configured uniformly, as clusters or as distributed clusters. Up to 64
devices, including the master, may be attached to a single DeviceNet network. Any of these, except the
master, may be a JDM. A typical system will include a master, such as a PLC or industrial PC, and
multiple slave devices, including a JDM with connected Modbus devices.
1.3 JDM Basic Operation
The JDM operates as the DeviceNet front-end gateway between the DeviceNet system and the Modbus
devices. It is a DeviceNet slave device that can be assigned by the system implementer to one specific
master. The DeviceNet Master can receive and send data to and from the JDM via the methods described
in this section. It interprets messages received from the DeviceNet connection and reformats and sends
them to the Modbus device. Likewise, it accepts and interprets responses from the Modbus device, which
are reformatted and passed back to the DeviceNet system as required.
The JDM has one DeviceNet address. All DeviceNet messages to the JDM itself (to read / write its internal
data) are sent to this address. All DeviceNet messages to and from the Modbus devices are sent to the
JDM DeviceNet address.
The JDM Parameter Object allows you to define the specific operation of each JDM. These parameters
include set-up for the serial comm link and the fault and idle actions and data.
Each Modbus device connected to the JDM has a Modbus address between 1 and 254. This address is
used by the host system and the JDM to identify which device on the Modbus network is being selected