OPTO 22 SNAP-PAC-EB1, Руководство пользователя

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COMMUNICATION OPTIONS
SNAP PAC Brains User’s Guide
10
• OptoDataLink exchanges I/O point data with ODBC-compliant databases, including Microsoft
SQL Server, Microsoft Access, MySQL, and others. OptoDataLink can be purchased separately or
as part of PAC Project Professional.
• SMTP (Simple Mail Transfer Protocol) connects a SNAP PAC brain with corporate email servers,
so employees can be emailed or paged if there’s a problem on devices attached to the brain.
• SNMP (Simple Network Management Protocol) makes it possible to monitor devices attached
to SNAP PAC brains just as you would any computer or server on the Ethernet network, using an
SNMP-based enterprise management system such as Computer Associates’ Unicenter
®
,
Hewlett-Packard’s OpenView
®
, or IBM’s Tivoli
®
. When a monitored event occurs, such as a door
left open or a pressure level too high, the brain sends an SNMP trap to the management
system.
• FTP (File Transfer Protocol) can be used to transfer files and data to and from the SNAP PAC
brain, whether to custom applications, enterprise databases, or any file system.
• Custom software applications are easy to develop using our OptoMMP Communication
Toolkit with ActiveX components and C++ classes. They use the OptoMMP protocol, an IEEE
1394-based protocol, to read and write to SNAP PAC brains. For developers not using Microsoft
Windows, our OptoMMP protocol is open and documented.
Simultaneous Communication
In addition to communicating using all the methods listed above, each SNAP PAC brain can also
communicate
simultaneously using all of these methods.
The reason lies in the nature of IP. In serial communication, a single data request is sent by one device
to another. The first device must wait for a response before any additional communication can be
carried out. IP, however, can establish multiple simultaneous sessions, so many data requests can be
sent at once without waiting for any individual response. Each request gets a response, but the link
isn’t idle while waiting for responses.
In addition, IP can simultaneously handle multiple requests from multiple devices. A PC can
communicate with all SNAP PAC brains and controllers on the same network—all at the same
time—and multiple PCs can communicate with one SNAP PAC device at the same time.
So, for example, a SNAP PAC brain can respond to directions from a Modbus master, give analog
point data to a technician using PAC Manager, and carry out instructions from a custom C++
application—all at once.
Accessing SNAP PAC Brains Over the Internet
Since SNAP PAC brains are just like any other hardware on the Ethernet network, you can access
them over the Internet in exactly the same way you would access a computer. The details depend on
your network and Internet connection. Consult your system or network administrator or your
Internet Service Provider (ISP) for more information.