Not that long ago, bigger was better when it came to PLCs. Racks of powerful controllers were needed to ensure proper levels of communication and control on the manufacturing floor-,even if some of the controller features were not needed. The thinking was to start big and move to smaller controllers down the line.
A current trend in automation is to use micro PLCs as affordable and flexible alternatives. Combining power supply, I/O, and a processor in one package, micro PLCs are often half the price of larger controllers, while retaining many of the same features and functions.
Siemens Energy & Automation has now given electrical engineers and designers another reason to consider micro PLCs. The company has introduced the Simatic CP 243-1 IT Communications Module, an affordable and easy-to-program Ethernet module with information technology functionality.
According to John Wilhite, Siemens S7-200 marketing manager, the Simatic IT module gives Simatic S7-200 PLC users a new level of communications flexibility. "With the S7-200 micro PLC, we now can communicate in the same manner that required a larger PLC two or three years ago," he says. "The Simatic IT module allows users anywhere in the world to communicate with one or more S7-200 PLCs or other S7 controllers via Ethernet and the web. In the past they would have to upgrade to a larger PLC."
The new module provides HTML process information to a standard web browser through Industrial Ethernet. This means information can be shared on a company's local intranet or viewed via an Internet browser from remote locations that don't have access to the company's network.
Real-time PLC data logging, data gathering for analysis, machine documentation, and HTML web pages are stored in the module's 8 MB memory.
Data from the module and the S7-200 controller (including failure messages, facility status, cyclic notification, and immediate failure detection) is transmitted to or retrieved from any other computer via standard file transfer protocol (FTP) services. Event-controlled messages are sent in plain English text by e-mail with updated process data.
According to Wilhite, the Simatic IT module is easy to program and install using wizards in the Step7-Micro/WIN programming software. "There are four IT CP wizards that ask users a series of questions," Wilhite says. "The step-by-step process automatically generates the PLC and module configuration and eliminates complicated and time-consuming programming."
The first IT CP wizard is standard and walks users through the module setup and configuration. Communication is based on TCP/IP and ISO standards. It includes a factory-installed MAC address, peer-to-peer communications with other S7 controllers, up to eight connections, and client or server configurations.
The other three wizards are optional. One establishes a user account for each person accessing the module. An e-mail wizard creates and stores messages in the module that can be sent when triggered by the PLC. An FTP wizard allows the module to perform file transfers with any other FTP server.
"Now plant personnel can be anywhere in the world and get information from a micro PLC," says Wilhite. "They can pull up the web site and see real-time data, as well as historical data."
While commonly found in larger PLCs, this level of information technology implementation is new to the micro PLC. "The Simatic S7-200 module will allow our S7-200 customers to easily implement information technology-level services to reduce downtime and ultimately enhance their businesses," concludes Wilhite.
For more information, call 800/964-4114 or browse to www.sea.siemens.com.