Momentum Modbus Plus 170 PNT Series Uživatelská příručka stáhnout pdf (Strana 144)

Using the Modbus Plus Ports

144

870USE10110 July 2004

Modbus Plus Addresses in Networks with Momentum Components

Introduction Modbus Plus devices function as peers on a logical ring. Each device accesses the

network by acquiring a token frame that is passed in a rotating address sequence.

Each device on a Modbus Plus network needs a unique address in the range 1...64.

The device address determines the logical order in which the network token will be

passed from device to device.

Address

Sequence

The assignment of addresses does not have to map to the physical layout of the

network–e.g., device 17 is placed physically before device 3. This is important to

understand because the network's token rotation is defined by device addresses-

e.g., device 2 will pass the token to device 3, device 3 to device 4, etc.

Illegal Addresses If you set the node address to 00 or to a value greater than 64:

The COM LED will go ON steadily to indicate an illegal address assignment.

The Run LED will flash 4 times.

The processor adapter will not run until you set a valid, unused address on the

option adapter and cycle power.

COMMUNICATION ERRORS MAY RESULT

Failure to assign a unique address to a device or two identical addresses on the

same network will cause communication errors and network problems.

Do not install a Modbus Plus option adapter before you have set its Modbus Plus

address for your application.

See your network administrator to get the Modbus Plus node address for this

module.

Failure to follow this instruction can result in injury or equipment damage.

CAUTION

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Momentum Modbus Plus 170 PNT Series Uživatelská příručka Strana 144