Monday, April 4, 2011

Communication Choices of MicroLogix 1200 Programmable Controllers

All MicroLogix 1200 programmable controllers provide several communication options to fit into a variety of applications. The DF1 Full-Duplex protocol allows the MicroLogix 1200 to communicate directly with another device, such as a personal computer or an operator interface device. The protocol of DF1 Full-Duplex is useful where RS-232 point-to-point communication is required.

The capability of DH485 multi-drop communication allows you to network up to 32 MicroLogix or SLC 500 controllers, Human Machine Interface (HMI) devices and/or personal computers using peer-to-peer messaging. And, the MicroLogix 1200 can communicate on a DeviceNet network as well. DeviceNet digitally links sensors, actuators, push buttons, PLCs and other industrial devices on an open network.

MicroLogix 1200 controllers also support DF1 Half-Duplex Slave communications for use in SCADA systems as a Remote Terminal Unit (RTU). This protocol of open network enables MicroLogix controllers to communicate as responder (slave) nodes on DF1 master/slave networks. DF1 supports up to 254 responder with a single master. Additionally, the MicroLogix 1200 supports Modbus Slave, a SCADA/RTU protocol.

• Standard RS-232 port
• The baud rates are 300, 600, 1200, 4800, 9600, 19,200, and 38,400
• RTS/CTS Hardware handshake signals
• Connection to DH485 and DeviceNet networks through 1761-NET-AIC and 1761-NET-DNI, respectively
• Connection to modems for remote communications
• ASCII messaging provides dial-out capability
The MicroLogix 1200 allows to choose the network that best meets your needs.

Use DeviceNet via the 1761-NET-DNI, If your application requires:
• Low-level multi-vendor devices connection directly to plant floor controllers
• Data sharing between 64 devices
• Better diagnostics to improve data collection and fault detection
• Reduced start-up time and less wiring than traditional, hard-wired systems

Use DH485 via the 1761-NET-AIC, If your application requires:
• Cell-level and plant-wide data sharing with program maintenance
• Data sharing between 32 controllers
• Program download, upload, and monitoring to all controllers
• Compatibility with multiple Allen-Bradley HMI devices

Use DF1 Full-Duplex DF1 Half-Duplex Slave, If your application requires:
• Connection to dial-up modems for data collection or remote program maintenance
• Connection to leased- radio modems or line for use in SCADA systems
• Remote Terminal Unit (RTU) functions

Use Modbus RTU Slave, If your application requires:
• Connection to modems for collection of remote data in a SCADA system
• Remote Terminal Unit (RTU) functions


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