Sram Red
Sram Red
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 SRAM PG 1070 Cassette 11 32t New Sram Force Level Road or MTB Compatible  US $69.00
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 Sram Red OG 1090 10 Speed Cassette 11 28 NIB LOW $ US $182.99
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 SRAM red Casette 11 28 10 Speed US $169.00
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 SRAM RED OG 1090 11 26 Cassette One Piece SHIMANO 10 Speed NEW US $169.97
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 SRAM Red OG 1090 10 speed 11 28 Cassette powerdome US $174.00
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 SACHS LY 93 12 21 8 speed screw on cluster vintage rare US $3.82
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 Sram RED Cass 11 26 take off US $100.00
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 SRAM PG 1050 11 28 10 SPEED BIKE CASSETTE XX Red Rival Force SHIMANO Compatible US $54.95
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 NEW SRAM CHAIN 10 SPEED 1070 114 LINKS 265 GRAMS SHIMANO 10 SPEED COMPATIBLE US $30.00
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 SRAM RED Black Edition Powerdome Cassette 11 28 US $134.50
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 Sram RED cassette New US $99.00
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 Sram Red 10spd Cassette OG 1090 11 26T US $175.00
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 SRAM PG 1070 Cassette 11 28t US $69.00
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 Sram Red OG 1090 10 Speed Cassette 11 26 NIB LOW $ US $174.99
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 Sram Red 10 Spd CS OG 1090 Road 11 23T Cassette 2012 New US $189.95
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 SRAM RED OG 1090 11 28 10 SPEED ROAD BIKE CASSETTE SHIMANO Compatible ULTRALIGHT US $190.00
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 NEW SRAM Red OG 1090 11 28T Cassette 10 SPEED Black US $184.25
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 SRAM RED Cassette 11 26 US $10.50
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 2011 SRAM RED OG 1090 bike cassette 11 23 10 speed New US $174.99
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 SRAM PG 1050 10 speed 12 36 Cassette Brand new in Box no reserve US $26.00
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 New SRAM Red Road Bike OG 1090 Cassette 11 26T 10 speed US $239.00
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 SRAM PG 1050 12 36 10 SPEED BIKE CASSETTE XX Red Rival Force SHIMANO Compatible US $54.90
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 SRAM PG 1050 11 32 10 SPEED BIKE CASSETTE XX Red Rival Force SHIMANO Compatible US $64.90
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 SRAM RED OG 1090 11 28 10 SPEED ROAD BIKE CASSETTE SHIMANO Compatible POWERDOME US $190.00
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 SRAM RED BLACK OG 1090 Road Cassette 11 26 10 sp US $199.99
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 SRAM RED BLACK OG 1090 Road Cassette 11 28 10 sp US $199.99
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 SRAM RED CASSETTE OG 1090 NO RESERVE 168 GRAMS US $2.75
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 SRAM PG 1050 11 23 10 SPEED BIKE CASSETTE Red Rival Force SHIMANO Compatible US $64.90
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 Sram Red Powerdome 11 25 Cassette NO Reserve US $110.00
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 Sram Red Powerdome 11 23 Cassette NO Reserve US $110.00
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 SRAM OG 1090 Red Black Edition Cassette 11 26 US $195.00
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 SRAM PG1070 1070 X9 10 Speed MTB Mountain Bike PowerGlide Cassette 11 36t US $88.61
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 SRAM OG 1090 Red Black Edition Cassette 11 23 US $195.00
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 11 25 Fast Free US Ship Sram Red BLACK OG 1090 10 Speed Cassette NIB LOW $ US $178.99
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 SRAM PG 1070 CASSETTE 11 23 SRAM CASSETTE RIVAL FORCE RED PG CASSETTE US $.99
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 SRAM PG 1070 CASSETTE 11 26 SRAM CASSETTE RIVAL FORCE RED PG CASSETTE US $10.49
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 Sram Red OG 1090 FAST FREE US Ship 10 Speed Cassette 11 25 NIB LOW $ US $174.99
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 SRAM PG 1050 CASSETTE 11 28 SRAM CASSETTE RIVAL FORCE RED PG CASSETTE US $1.29
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 SRAM Red OG 1090 11 23T 10s Cassette NEW US $155.99
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 Sram 2011 Red Black OG 1090 Road Bike Cassette 11 23 US $249.95
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 Sram Red 11 23 Og 1090 Cass Maybe 200 Miles US $22.50
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 SRAM RED OG 1090 11 26 T Cassette Good Condition US $23.50
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 NEW 2011 SRAM RED BLACK OG 1090 Cassette 11 26 Power Dome US $179.00
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 SRAM Red OG 1090 10 Speed 11 25 Cassette US $202.00
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 SRAM Red 10 Speed Cassette NEW US $1.25
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 SRAM PG950 950 9 Speed MTB Mountain Bike PowerGlide Cassette 11 32t US $51.82
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 SRAM Red OG 1090 road bike Cassette 10sp 11 26 NEW US $199.00
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 SRAM Red 10 Speed Cassette NEW 11 25 US $1.25
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 SRAM Red OG 1090 10 speed 11 28 Cassette US $263.95
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 SRAM Red OG 1090 10 speed 11 23 Cassette US $249.09
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Ethernet Switches?
Why Use Industrial Ethernet Switches?
1. Benefits of Industrial over Commercial Switches
Industrial Ethernet switches are housed in rugged industrial style steel enclosures using Din-Rail or panel mounting. Most commercial switches and media converters cannot mount conveniently inside equipment enclosures.
Another added benefit derived from using Industrial Ethernet switches is redundant power inputs. Commercial switches rely on a single power supply to power the switch, while Industrial switches typically run off DC power, and have redundant power inputs. This allows the weakest link (the power supply) to have a hot standby back up, insuring maximum up time.
Industrial Ethernet switches carry a Class I Div 2, group ABCD rating while the commercial counterparts do not. This allows the Industrial Ethernet switches to operate where explosive gases are being used (very typical for industrial applications).
2. Alternatives
Because Ethernet has been available in the office environment long before industrial Ethernet equipment existed, the equipment is well known for its performance and reliability and low cost. Quite often, when companies evaluate the technology, they do not examine the alternatives of purchasing Industrial Ethernet Switches versus commercial switches and routers. However, In this instance, the evaluation is simple. Fortunately, Industrial Ethernet switches provide advantages over the 4 primary alternatives being used. All of these alternatives utilize commercial Ethernet switches and hubs, and are listed below:
• Wire all connections to a climate-controlled environment.
In this scenario, the customer will place commercial network equipment in a climate controlled environment and run cable to every industrial Ethernet node. This is very costly and decreases reliability. Industrial Ethernet switches offers the opportunity to eliminate significant, expensive wiring efforts when compared to this approach.
• Build climate-controlled environments in harsh areas.
In this scenario, the customer, to reduce wiring costs, will build a climate-controlled environmental enclosure to house commercial equipment in a harsh environment (i.e. Nema 4 enclosures with Peltier coolers and bulkhead-mounted connectors). This is very costly and increases the number of components that can fail. Industrial Ethernet Switches can be installed directly in harsh locations, thus eliminating the need for expensive climate-controlled enclosures.
• Simply use commercial equipment without regard to environmental mismatches.
This is an alternative, but not a very good one. In this scenario, the customer utilizes commercial equipment in the harsh environment. This equipment is not rated for these environments and will probably fail and/or decrease the reliability of the system. In our discussions with customers utilizing this alternative, it was only implemented because they were not aware that industrial grade equipment was available. They are very open to utilizing Industrial Ethernet Switches.
In addition, many commercial switches use cut-through techniques, and can propagate bad packets on the network. However, Industrial switches use store and forward technology that perform CRC (cyclic redundancy checks), and insure the data Integrity of any packets being forwarded.
• Utilize Hubs instead of Switches
While hubs are cheaper than switches they do not eliminate collisions, and hence create determinism issues associated with Ethernet Networks. The following discussion illustrates the basic difference between switches and hubs.
Difference between Ethernet Switches and Hubs
A hub, also known as a repeater, is a simple device that connects Ethernet nodes. Hubs forward data packets they receive from a single workstation to ALL ports. All users connected to a single hub or interconnected hubs share the same bandwidth. As nodes are added to the network, they compete for a finite amount of bandwidth (typically 10 or 100 Mbs). Therefore, data collisions are guaranteed when a hub is used and network determinism (the ability to guarantee a packet is sent/received in a finite amount of time) is impossible. This is the primary reason Ethernet has historically not been accepted in control applications. Most control systems have a definite time requirement for packet transmission (< 100ms). This cannot be guaranteed with a hub and is especially if the network is busy. You can imagine the problems this can cause in a mission critical control application.
This is analogous to a single lane road. You cannot get onto the road until traffic is clear. With a hub, you cannot send a packet until network traffic is clear.
Another analogy is a party line phone. If you shared a party line phone with 8 users, anytime any of the users received a call; your phone would ring. All users would have to answer to determine if the call was for them. In addition, no other user can use the phone while someone else is using it.
An Industrial Ethernet Switch is a more complex device with built in intelligence to connect Ethernet nodes. The switch eliminates the problem of network determinism by providing full bandwidth with storage to a node or group of nodes. The switch eliminates all collisions that typically make Ethernet nondeterministic. A switch sends data only to the appropriate network port or segment, not the entire network as a hub does. The switch forwards data based on the MAC address (unique for each hardware device on the network) contained in the data packet. The switch must store the MAC addresses of every device it communicates with, requiring high-speed dual ported SRAM (hubs have no memory requirements). The switch determines the location of each node and establishes a temporary connection between itself and the node and terminates once the packet is transferred.
Using our highway analogy, we have turned the single lane road into an 8-lane highway. A lane can be dedicated to mission critical nodes insuring traffic can always get through in a pre-determined time.
Using the phone analogy, your phone rings only when the call is for you and you can use the phone when other people are using it.
Summary
In summary, an Industrial Ethernet Switch increases network bandwidth and provides network determinism for Industrial control applications, and provides the most cost effective solution for industrial environments. You can look up www.control-logic.com.au for detailed information on various options in Australia and their respective comprehensive product range.
About the Author
Leon Cowper has been selling electrical components and supplies through his store since 1996. Today he is an expert on all types of products and companies in the field.
www.control-logic.com.au