Engineered Synergistic Interoperability
SNMP The Synergistic Solution to the Problem You May Not Know About But Will Consider Very Important!
is the most important thing on the mind of a
manufacturing professional? Well, from most articles we
read, there are two areas improving manufacturing
performance and reducing downtime with a wide array of
solutions available to assist you with both. You can
focus on integration with your business systems to
improve the real-time aspects of production management
and you can focus on better production analytics to
squeeze additional performance out of the equipment you
are monitoring. Both identify and resolve areas of
production stress the items that impact the
reliability of your manufacturing equipment. These are
all valuable pursuits and they will, no doubt, deliver
improvements in your production and profitability. To
effectively calculate the savings, you should quantify
your cost of downtime, per machine, per line, per plant
area, etc. Only then, will you really clearly know the
return on your investments.
But as was said in a song "The real troubles in your life are apt to be things that never crossed your worried mind: the kind that blind sides you at 4pm on some idle Tuesday."
What might they be? Let's start simple that production printer that is left off-line or that ran out of ink or paper. The Storage Disk that filled up. On the more disruptive side it's the CD left in a Drive that stops a system from Auto-Booting. The operator that started a video session and stole all available network bandwidth It's the laptop plugged into an available switch port to access a PLC needing maintenance (oops yes, I let my kids use it to do homework the other night and hmmm I guess they may have accidentally infected it). How do you monitor and protect against all this?
|SNMP - Simple
Network Management Protocol, is a communications protocol
built into most of the IT infrastructure around us. From
Printers to UPS Systems, Routers and the PCs we use in
automation, virtually everything in the IT world supports
SNMP communications. It is already there, waiting for
your use. And, it is supported over the Ethernet you are
So, what does this all mean? Well, it means you can both monitor and control most of the equipment making up your system infrastructure. You can monitor that printer and make sure it is on-line and has the resources it needs for this production shift. You can monitor for media left in drives or measure the UPS reserve power to make sure it is ready for that power interruption. Plus monitor your network for normal bandwidth so that you can generate alarms on abnormal situations. You can even disable unused ports on a switch to ensure someone doesn't just plug-in a maintenance laptop without first following procedures to ensure the safety of your automation environment.
Monitoring devices via SNMP has typically been the domain of your IT personnel. They have tools such as HP OpenView enabling them to discover and monitor the various bits that make up your business infrastructure. Ah yes, but they can't tell a PLC from an SLC and you really don't want them performing a port scan of your automation network. No, that really wouldn't be a good idea, unless you like the idea of a Tuesday evening infrastructure troubleshooting session So, what do you do? You know now that you already have most of what you need in terms of devices that can give you SNMP results, all that's missing is the integration of SNMP data with your existing HMI/SCADA solution.
the solution comes in the form of an Industrial SNMP
(iSNMP) driver, similar to your RSLinx, ProfiNet, Modbus,
etc. automation driver. An iSNMP Driver will let your
automation system both monitor and manage your automation
infrastructure. In addition to monitoring your PLCs and
Field Devices, you will be able to communicate with all
the pieces that make up your automation network, the
backbone of your plant.
Here's SNMP 101. Devices that support SNMP are described as having SNMP Agent capability. The Agent communicates with the device and exposes information based on the SNMP Communications Standard. The SNMP Standard however, does not describe the data that is available from a device. That is handled by a separate definition called a MIB (Management Information Base) file. Devices that include an SNMP Agent will have a corresponding MIB File, either available with the device or easily accessible from the manufacturer. The MIB describes the information that is available, and how to interact with the device. Some data is read-only; other data can be read or written to.
SNMP commonly supports two types of connections, one for the polling of data (A GET Command) and another for the generation of unsolicited messaging based on triggers called TRAPS. A SET command also exists for the management of a device writing information to a device.
have a look at some MIB Variables for common
devices used in Automation.
The display above highlights the KEPServerEX configuration environment and an auto-generated list of Tags typical of an SNMP Managed Switch.
Kepware's KepserverEX OPC server offers Ethernet connectivity through their library of Drivers for many of today's most commonly used PLCs, PACs, DCSs and other control devices:
The combination of device drivers, SNMP support and Ethernet hardware available through ESI ultimately provides our customers with a "best of class" solution.
|Note: Foundation of article provided by Kepware. Additional information has been added to customize this article, based on ESI's product offering.|
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