Communication Specifications

Original instructions

Introduction

The BMENOC0321 control network module provides support for using and .

These specifications describe the I/O communication and the and messaging capacities of the BMENOC0321 modules.

NOTE: The maximum I/O scanning capability for a BMENOC0321 module is 5,500 packets per second.

I/O Communication Specifications

These tables present the I/O communications features of the BMENOC0321 module.

EtherNet/IP (CIP Implicit Messaging):

Feature		Maximum Capacity
scanner	number of devices	128 (EtherNet/IP devices and local slaves)
scanner	message size	input: 505 bytes (including header) output: 509 bytes (including header)
adapter	number of instances	12 adapter instances
	number of connections	2 connections per instance
	message size	511 bytes (including header)
	inputs	505 bytes (including header)
	outputs	509 bytes (including header)

Modbus TCP (Modbus I/O Scanner):

Feature		Maximum Capacity
registers	number of devices	128 devices shared with EtherNet/IP
	read	125 registers
	write	120 registers
message size	read	250 bytes (125 words) (excluding header)
message size	write	240 bytes (120 words) (excluding header)

Combined EtherNet/IP Scanner/Adapter and Modbus Scanner

I/O Data Exchange with the CPU
Feature	Maximum Capacity	Comment
input data size	4 KB (2 K words)	4 KB of data includes user configurable data and overhead. The overhead includes module diagnostic data, data object headers, and the number of headers depending on the user configuration. As a result, the user configurable data size is less than 4 KB, but more than 3.5 KB.
output data size	4 KB (2 K words)	4 KB of data includes user configurable data and overhead. The overhead includes module control data, data object headers, and the number of headers depending on the user configuration. As a result, the user configurable data size is less than 4 KB, but more than 3.5 KB.

Explicit Messaging Specifications

These tables present the explicit messaging features of the BMENOC0321 module.

NOTE: These tables report the maximum capacity for a single BMENOC0321 module. For more information, refer to the performance characteristics and capacities for M580 CPUs in the Modicon M580 Hardware Reference Manual.

EtherNet/IP (CIP explicit messaging):

Feature		Maximum Capacity
client	simultaneous requests	16
client	message size	1024 bytes
server	simultaneous requests	32
server	message size	1024 bytes

Modbus TCP (Modbus explicit messaging):

Feature		Maximum Capacity
client	simultaneous requests	16
client	message size	1024 bytes
server	simultaneous requests	32
server	message size	1024 bytes

A network communication protocol for industrial automation applications that combines the standard internet transmission protocols of TCP/IP and UDP with the application layer common industrial protocol (CIP) to support both high speed data exchange and industrial control. EtherNet/IP employs electronic data sheets (EDS) to classify each network device and its functionality.

(Modbus over TCP protocol) This is a Modbus variant used for communications over TCP/IP networks.

UDP/IP-based class 1 connected messaging for EtherNet/IP. Implicit messaging maintains an open connection for the scheduled transfer of control data between a producer and consumer. Because an open connection is maintained, each message contains primarily data, without the overhead of object information, plus a connection identifier.

TCP/IP-based messaging for Modbus TCP and EtherNet/IP. It is used for point-to-point, client/server messages that include both data, typically unscheduled information between a client and a server, and routing information. In EtherNet/IP, explicit messaging is considered class 3 type messaging, and can be connection-based or connectionless.

An Ethernet service that continuously polls I/O modules to collect data, status, event, and diagnostics information. This process monitors inputs and controls outputs. This service supports both RIO and DIO logic scanning.

An adapter is the target of real-time I/O data connection requests from scanners. It cannot send or receive real-time I/O data unless it is configured to do so by a scanner, and it does not store or originate the data communications parameters necessary to establish the connection. An adapter accepts explicit message requests (connected and unconnected) from other devices.