Communication protocol support

Modbus is a half-duplex, master-slave communications protocol that allows a single master to communicate with a maximum of 247 slave devices. The Modbus network master reads and writes bits and registers. Modbus RTU is supported by configuring the serial port as Modbus RTU.

For more information about the Modbus protocol, refer to the Modbus Protocol Specifications.

The Modbus/TCP Server communication protocol uses the same Modbus mapping features as Modbus RTU, but it is supported over the Ethernet instead of through a serial port.

The L50E controller supports up to 16 simultaneous Modbus TCP Server connections. No protocol configuration is required other than configuring the Modbus mapping table.

L20E and L50E controllers support up to 16 simultaneous EtherNet/IP server connections through an embedded Ethernet communication channel. The channel can be used to connect an L50E controller to various devices through a local area network using a 10 Mbps/100 Mbps transfer rate.

The CIP protocol is a transport and application layer protocol used for messaging over EtherNet/IP, ControlNet, and DeviceNet networks, which allows HMIs to easily connect to an L50E controller.

The CIP protocol is used for explicit messaging. Explicit Messaging (configuration, data collection, and diagnostics) is used to transfer data that does not require continuous updates. Explicit messaging is supported using CIP Generic client messaging through the MSG_CIPGENERIC function block and using CIP Symbolic client messaging through the MSG_CIPSYMBOLIC function block.

CIP serial uses DF1 full-duplex protocol and provides point-to-point connection between two devices. It combines data transparency (American National Standards Institute ANSI - X3.28-1976 specification subcategory D1) and two-way simultaneous transmission with embedded responses (subcategory F1).

L50E controllers support CIP serial through an RS-232 connection to external devices, such as computers running

RSLinx® Classic

software,

PanelView

Component terminals (firmware revisions 1.70 and later), or other controllers that support CIP serial over DF1 full-duplex, such as

ControlLogix®

and

CompactLogix

controllers that have embedded serial ports.

The serial port driver can be configured as

CIP serial

,

Modbus RTU

,

ASCII

, or

Shutdown

through the device configuration tree.