SNAP-PAC-R1-W OPTO 22, SNAP-PAC-R1-W Datasheet - Page 2

• Manufacturer Part Number: SNAP-PAC-R1-W
• Description: Programmable Controller Wireless
• Manufacturer: OPTO 22

Specifications of SNAP-PAC-R1-W

• Accessory Type: Programmable Automation Communication
• Signal Input Type: Ethernet, RS-232
• Rohs Compliant: Yes
• For Use With: SNAP PAC System
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Wireless PACs and I/O in Industrial Automation
Network Performance and Reliability
The reliability of a wireless network depends on a number of things,
including network size, physical environment, number of network
users and how heavy their use is, and interference from other devices.
For a small all-wireless network, devices may perform well in ad hoc
mode (peer to peer), where each device can detect and communicate
with any other similarly configured device within range. This mode
requires a smaller expenditure on network hardware and can be
especially useful for a temporary wireless network. For a larger
network, infrastructure mode is usually more suitable. Infrastructure
mode routes communication through one or more wireless access
points (APs).
Since wireless communications are
based on radio signals that travel
through air, physical environment
plays a clear role in how well the
network performs. Any obstacle—
wood, metal, concrete—will
impede the signal as it travels. The
solution is to strategically place APs,
wireless routers, and wireless
repeaters as needed to cover the
entire area requiring wireless
transmission.
Network reliability also depends on
the number of network users and
the nature of their use. Simple data
transfer usually requires little
bandwidth; heavier use, such as
transferring large files or interacting
with multimedia, can slow network
traffic considerably. Networks using
the 802.11a or g standard are faster
(maximum 54 Mbps) than those
using 802.11b (maximum
11 Mbps).
RF (radio frequency) interference
and EMC (electromagnetic
compatibility) problems reduce network reliability when other
devices—such as cordless phones, Bluetooth devices, even
microwave ovens—interfere with wireless signal reception.
Reducing interference from other devices may involve changing
channel frequency within a range or moving into a less crowded
frequency. Wireless networks compatible with 802.11b and g
standards, for example, use 2.4 GHz, a frequency shared by many
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devices. Moving to an 802.11a-compatible system, which uses 5 GHz,
might offer less interference, although range may be shorter.
Wireless standards also differ in the number of non-overlapping
channels they allow: 802.11b and g allow only three, so frequencies
must be reused when more than three APs are required in the same
system. More channels are available in 802.11a.
Availability and Cost of I/O Components
While concerns about wireless security and performance are generally
shared by users of all wireless networks, the concern about availability
and cost of I/O components is unique to the automation industry.
mean costly workarounds or even eliminating wireless as a possibility.
To set up any size wireless network, automation engineers usually find
they must buy special wireless components, such as module carriers,
I/O modules, racks, and terminations. In nearly all cases, customers
who install a wireless network for automation must carry a separate
inventory of spares in addition to those required for their wired
systems. Special components and additional spares increase the cost
of a wireless system.
Currently, most automation
manufacturers who supply wireless
products offer product lines that
differ substantially from their
regular lines.
A wireless solution may have been
acquired by purchase or developed
by a separate division, for example.
Or a subset of the regular product
line may be adaptable for wireless
use by module carriers or similar
devices.
However, these solutions can cause
problems for the automation
customer.
As part of a separate wireless line or
as a subset of regular products,
wireless I/O may not include
features the application requires—
or features that just make design
easier, such as simpler methods of
wiring to field devices. If an
application needs specific signal
inputs or channel-to-channel
isolation, for example, the wireless
I/O product line may not include
them. Limited availability may