COMMUNICATION OPTIONS
SNAP PAC R-Series Controller User’s Guide
14
•
EtherNet/IP
provides communication with Allen-Bradley ControlLogix® and CompactLogix™ PLC
systems and other systems using the EtherNet/IP protocol. Both implicit and explicit messaging are
supported.
•
Modbus/TCP
provides a direct connection with Modbus/TCP hardware or software or third-party
software applications, which can read or write to I/O points on SNAP PAC R-series controllers.
•
OPC
(OLE for Process Control) uses OptoOPCServer to serve controller data to any OPC 2.0-compliant
application, such as an HMI, which can also read or write to I/O points. OptoOPCServer can be purchased
separately or as part of the PAC Project Professional software suite.
•
SMTP
(Simple Mail Transfer Protocol) connects a SNAP PAC R-series controller with corporate email
servers, so employees can be emailed or paged if there’s a problem on devices attached to the controller.
•
SNMP
(Simple Network Management Protocol) makes it possible to monitor devices attached to SNAP
PAC R-series controllers 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 controller 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 R-series
controller, whether to custom applications, enterprise databases, or any file system. R-series controllers
manufactured after November 2008 include removable storage capability: a microSD card slot. See
for information on using the card for storage and for loading firmware or PAC Control strategies
to the controller.
Simultaneous Communication
In addition to communicating using all the methods listed above, each SNAP PAC R-series controller can also
communicate
simultaneously
using all applicable 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 R-series controllers on the same network—all at the same time—and multiple PCs can
communicate with one controller at the same time.
So, for example, a SNAP PAC R-series controller 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 R-Series Controllers over the Internet
Since SNAP PAC R-series controllers 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. Also see the
Guide to Networking Opto 22 Products
(form 1796).
