Ethernet on the Floor

InTech, Nov 2006 by Fondl, Mark

Every managed device keeps a database of values for each of the definitions written in the MIB. It is not the actual database itself; it is implementation dependent.

SNMP protocol

The basis of SNMP comes from the manager/agent model. SNMP is "simple" because the agent requires minimal software. Most of the processing power and data storage reside on the management system, while a complementary subset of those functions resides in the managed system.

To achieve its goal of simplicity, SNMP includes a limited set of management commands and responses. The management system issues Get, GetNext, and Set messages to retrieve single or multiple object variables or to establish the value of a single variable. The managed agent sends a Response message to complete the Get, GetNext, or Set. The managed agent sends an event notification, called a trap, to the management system to identify the occurrence of conditions, such as threshold, that exceeds a predetermined value. In short, there are only five primitive operations:

* Get: Identifies the object

* Get next: Response of the object

* Get: Response (indicative operation)

* Set: Sets new value or reports error

* Trap: Message from device indicating a condition

SNMP allows managers and agents to communicate for the purpose of accessing these objects.

Growth means management

As networks continue to grow almost exponentially, the need for control is critical. It is more evident in an already sensitive industry. The need for control over the applications and process and the sheer amounts of critical data a user must retrieve is greater than ever before. The ability to monitor, maintain, set alarms, visualize, and contact the proper personnel is critical and necessary in efficient network environments. It is not good to have an intricate, technologically sound network without sound network management.

Remote management

Another added benefit is the ability to remotely manage/monitor/configure a network or device. When there is a problem, a plant engineer can connect and view a particular device from a home computer using a Web browser instead of having to go to the plant and manually check it. Inversely, when there is a problem at the factory, you can configure the device through the management platform to contact the responsible person via e-mail or pager.

Not only will Ethernet extend further down to the lower level devices, but the technology behind them will grow also. Many more devices will have more capabilities as the chipsets from the manufacturers are becoming more compact with more features. There are full TCP/IP chipsets with on-board IO points and Web servers available for less than $15. This is a clear indication of where the technology is going.

RESOURCES

Automation Network Selection

http://www.isa.org/networkselect

Modem networked systems come with caveat: Industrial applications begin to reap the benefits of remote access. security breaches a concern.

www.isa.org/link/caveat

Water System Unplugs: Ethernet boosts efficiency at growing Canadian burgh and halts expensive quick fixes