Seven series of Industrial Ethernet products comprise the CTRLink family. Each series is broadly classified under the titles Hubs, Switches and Media Converters. A Hub implies a repeating hub, while a Switch refers to a switching hub. Media converters simply provide the means for converting between twisted-pair cabling and fiber optic cabling.
Modern Industrial Ethernet networks are wired in a star topology using either twisted-pair copper or fiber optic cabling. If the network connects more than two devices, a hub is required. There are two basic styles of hubs — repeating and switching.
Repeating hubs (aka repeaters) are the simplest of hubs — physical-layer devices that are ignorant of the information contained in the frames. These devices provide simple expansion of the network while complying with the rules for collision detection and reinforcement inherent in half-duplex, shared Ethernet networks. A maximum of four repeating hubs can be cascaded as long as they do not exceed the geographic limits of the collision domain or the constraints of cable distances. Repeating hubs operate at 10 Mbps and are available in the EI series of repeating hubs and the EIM miniature repeating hub.
Switching hubs (aka switches) are actually classified as bridges and, therefore, are data link devices. A bridge allows the linking of two or more separate Ethernet networks while separating the collision domains of each network. The advantage of using switches is that expansion rules are much simpler than for repeating hubs — allowing the cascading of switches (virtually without limit). Switches can also be configured for full-duplex operation — thereby eliminating the collisions that occur with half-duplex, shared Ethernet networks. Switches are available in the EIS Series, the EISM miniature model, the EISC (configurable) Series and three families of compact managed and unmanaged switches: the EICP, EISX and EISB Series.
Connecting a fiber network to a copper network can be accomplished with either a repeating or switching hub — with the extra RJ-45 jacks available for other local twisted-pair drops. If only one data path needs conversion, a media converter can do the job. Like repeating hubs, media converters are classified as physical-layer devices. Models are available in the EIMC Series of miniature media converters.

Protocols

Ethernet defines the physical and data link layers of the ISO Open Systems Interconnect Reference Model. There are numerous protocols that define the layers above the data link layer with the TCP/IP suite being the most popular. Above TCP, there are several application-layer protocols specific to the automation industry such as Ethernet/IP, PROFInet, HSE, MODBUS/TCP, iDA, BACnet and a host of proprietary protocols. Since CTRLink products are based upon Ethernet technology, they will operate with all of these protocols including TCP/IP. Protocols are not an issue when selecting CTRLink products.

Power Source

For safety and convenience, CTRLink products operate from unregulated or regulated low-voltage AC or DC power sources. DC voltages can range from 10–36 VDC. AC voltages range from 8–24 VAC, 47–63 Hz. Power consumption varies by model but is typically 5 watts or less. Multiple power connections are provided on CTRLink products to accommodate a wide range of power management strategies. CTRLink products can share power with other devices from a common control transformer with either a grounded or ungrounded secondary or from a common DC power supply. There is often no need for a separate transformer, but one is available if required. For DC-powered control panels, most models have extra connections for redundant power sources to accommodate standby battery systems. DC connections are reverse-voltage protected. The power connector is typically removable to ease field wiring.

Regulatory Compliance

CE Mark — All CTRLink products comply with the CE marking requirements of the European Union. In terms of Electromagnetic Compliance (EMC), the CTRLink products comply with the series of immunity and emission for Information Technology Equipment (ITE) under the industrial classification.
UL 508 (Industrial Control Equipment) — All CTRLink products conform to the requirements of UL 508 when powered from a Class 2 (low-voltage, energy-limited) power source. This is a popular industrial automation standard and is usually required of control panels.
UL 1604 (Electrical Equipment for Use in Class I and II, Division 2, and Class III Hazardous [Classified] Locations) — Some CTRLink models have been approved for certain portions of UL 1604. CTRLink listed equipment conforms to Class I, Division 2, Groups A, B, C and D and carries the temperature rating of T4A — allowing for an ambient rating of 60°C. This standard is found in the process industry.
UL 864 (Control Units for Fire-Protection Signaling Systems) — Some CTRLink products are recognized as components for UL 864. This standard, which is found in the building automation industry, requires that the Original Equipment Manufacturer (OEM) carry the actual listing. The recognized CTRLink products are considered components of that system.

Data Rates

The minimum data rate for Industrial Ethernet is 10 Mbps and some devices can only operate at that speed. However, other devices can operate at 100 Mbps, or at either speed. If all devices in a network can operate at 10 Mbps, it is possible to use a repeating hub. If 100 Mbps operation is necessary, a switching hub must be used. All CTRLink switching hubs are capable of operating at either speed. On copper ports, speed setting is accomplished through the auto-negotiation protocol or manually.
Fiber optic port data rate depends on the type of hub hosting the port. For repeating hubs, the rate is 10 Mbps. For switching hubs, the rate is 100 Mbps. Because of this difference, a repeating hub cannot link by fiber with a switching hub.

Temperature Range

All CTRLink products support the standard industrial temperature range of 0° to +60°C. This temperature range is consistent with companion equipment such as programmable logic controllers and industrial input/output modules mounted in non-ventilated, dust-tight or water-tight control panels. For outdoor applications where equipment is being mounted in either heated or non-heated enclosures, the EISX Series and the EISB Series support the extended –40°C to +75°C temperature range.

Mounting

Industrial control devices are usually mounted on a sub-panel of the control enclosure either by fasteners or by direct attachment to a DIN-rail. Most CTRLink products support either mounting method, but a few offer only one mounting method. The most common DIN-rail size is TS-35, but some CTRLink products also accept TS-32.

Enclosure

There are three major styles of CTRLink enclosures. The standard style is an aluminum enclosure 156 mm high. It is the most common enclosure style and provides the most ports (up to 24). For applications requiring a small size, the 79 mm high miniature plastic enclosure could be the solution. The remaining major style is the compact aluminum enclosure which is 96 mm high.
Apart from the miniature and compact styles mentioned above, two other product series offer space-saving dimensions in an aluminum enclosure. Skorpion models are 100 mm high and BAS models are either 84 mm or 89 mm high.
All CTRLink enclosures have an Ingress Protection rating of IP30 and are thus meant to be housed in the customer's control panel or equipment closet.

Functionality

All the CTRlink products will operate "right out of the box" and can be put into service with little or no adjustment. We call this "Plug and Play" (PnP) mode. In PnP, the CTRLink product automatically adjusts to its environment. With hub and media converter products, this is the standard mode of operation — making installation simple. However, some switch products offer several features, not available in hub and media converter products, that can be configured through a console port.
All switch products can operate in PnP mode and utilize the auto-negotiation protocol to set features such as data rate, duplex and flow control. These features are negotiated upon link start-up with the connected device. With a configurable product such as the EISC Series, these features can be set on an individual port basis. These configurable models also support advanced networking features such as trunking, Port VLAN and QoS — all utilizing the console port on the EISC for configuration.
The ultimate in switch functionality can be achieved with the management option in the EICP, EISX and EISB series. Configuration is achieved through either a console port or through a web server resident on the unit. By management, we mean that the device supports the Simple Network Management Protocol (SNMP) — providing additional monitoring and reporting functionality. The managed versions of these devices also provide advanced networking capability including port mirroring, IGMP Snooping, rate limiting, port security, multicast filtering and Rapid Spanning Tree Protocol.

Auto-negotiation Protocol

The auto-negotiation protocol is a Plug and Play feature found on CTRLink switches. It allows automatic configuration of port and connected device parameters based upon the highest common capabilities of the two partners. Parameters such as data rate, half- or full-duplex and flow control are set this way. For full-duplex operation, the PAUSE scheme can be used. For half-duplex operation, the back pressure scheme can be used. On some CTRLink products, auto-negotiation can be defeated — allowing ports to be manually configured. Fiber optic products do not support auto-negotiation so their parameters must be manually set.

Copper Ports

Shielded RJ-45 connectors are provided on all twisted-pair copper ports and these accommodate cable that is either UTP (Unshielded Twisted-Pair, much preferred) or STP (Shielded Twisted-Pair). The number of copper ports varies by model, up to a maximum of 24. These ports are all wired as MDI-X (internal crossover), the standard in Hub and Switch products. EIM and EISM models include an "uplink" (MDI) port for cascading Hubs or Switches via a straight-through cable. The EI and EIS Series require a crossover cable for cascading. All other models offer Auto-MDIX for automatic crossover connection.

Fiber Optics

All CTRLink products have at least one twisted-pair copper port, and on certain models either one or two fiber optic ports. One-port fiber optic models are for end-of-line applications and two-port fiber optic models support a daisy-chain fiber backbone scheme. Fiber connectors can be either ST or SC. On 10 Mbps models, 850 nm operation is supported for multimode fiber optic cable and ST connectors. On 100 Mbps models, 1300 nm operation is supported for either single-mode or multimode fiber optic cable. Multimode connectors can be either ST or SC, but only SC connectors are used on single-mode models.

Broadcast Storm Control

A broadcast is a transmission from one station to all other stations on the network and is usually used during a configuration process. Although not usually harmful, excessive broadcast messages by an errant station can consume the total bandwidth of the network — thereby, inhibiting other, more useful, messages from being passed. This broadcast "storm" can be minimized by those CTRLink products that have this feature invoked.

LED Indicators

All CTRLink products have LED indicators to assist the operator in understanding the state of individual ports on hubs, switches and media converters. Depending upon the model and complexity of the product, the LED indicator functionality can vary. What is usually indicated is Power, Link, Activity, Data Rate, Collision or Duplex.

Advanced Features Provide Higher Performance

All CTRLink products will operate in Plug and Play mode; however, additional functionality can be gained from both the configurable and managed switch models. These models support features that must first be properly configured before being put to use, but which provide the means for achieving higher performance.

Signal Strength Indicators

The EISC supports a unique feature of monitoring the signal strength on twisted-pair ports. A small bar graph display (available on one configuration screen) depicts received signal strength at each port. This is useful in troubleshooting cabling problems.

Fixed Port Settings

Setting port parameters such as data rate, duplex and flow control is usually accomplished using the auto-negotiation protocol. However, there are times when the user may want to preset these parameters to ensure quick and reliable startup. With the Fixed Port Settings feature, auto-negotiation can be disabled and individual parameters can be manually set for each port.

Fault Relay

On certain models a single Form A (normally open) relay contact is available for low-voltage signaling to a supervisory system — indicating a fault condition on the network. A common fault is loss of link on one of the switch ports. The fault relay can be programmed to trip on particular port conditions, and the contact sense (make-on-fault or break-on-fault) can be programmed as well.

Console Port

To configure the various advanced features on configurable and managed switches, a console port is available. It consists of a DB-9 male connector wired as a DTE port with the data rate set for 9600 baud (8-bits for data, no parity, one-stop bit). On EISC units, the console port connects to a serial port on a PC running a Windows®-based configuration program provided with the product. On managed switches, the console port requires a terminal or terminal emulation program such as HyperTerminal.

Modbus Protocol (RTU, Slave)

Modbus is a simple, well-known protocol for accessing various industrial devices from a single master. The EISC console port supports this protocol. For those individuals familiar with Modbus, it is quite easy to both configure and access the status of the EISC using function codes 3 (Read Holding Registers), 6 (Preset Single Register) and 16 (Preset Multiple Registers). This allows a supervisory host PLC to monitor the status of individual switch ports by way of register transfers.

Trunking

Trunking (aka link aggregation) is a method to increase the throughput of switch-to-switch or "backbone" connections. By assigning individual ports as trunk ports, parallel paths can be created between switches to increase throughput. The downside of this approach is a corresponding reduction in available ports used to connect devices.

Quality of Service (QoS)

Quality of Service is a means of granting priority to certain types of transmissions. There are several schemes. Some schemes assign priority on a port-by-port basis while other schemes examine a field in the Ethernet frame being sent. QoS support differs on configurable and managed switches.

Virtual Local Area Network (VLAN)

A VLAN allows the logical separation of network traffic through common switches — yielding higher performance and higher network security. Ports on the switch must be assigned to individual VLANs; thereby, restricting VLAN traffic to only those ports. Both configurable and managed switches provide VLAN support.

Simple Network Management Protocol (SNMP)

A managed switch functions as an SNMP agent and maintains a set of standardized objects such as MIB II (Management Information Base) to provide information on the status of the various ports on the switch. Traps can also be set by management software to trigger on events of interest in the switch operation.

Auto-MDIX

This feature provides an automatic crossover function — eliminating the need for a separate uplink port or a crossover cable. Ports with Auto-MDIX enabled will determine the proper connection upon linkup.

Port Mirroring

Switches restrict communication to only those ports directly involved with a particular transmission. This reduces traffic by eliminating these same transmissions to ports which are not involved. This switch feature makes it difficult for monitoring transmissions with a tool such as a protocol analyzer. By using the port-mirroring feature of a managed switch, traffic from one or more ports can be replicated on another port for monitoring purposes.

Multicast Filtering

A multicast is a transmission from one station to many other stations in a multicast group. Since a switch is usually unaware of the location of the intended stations, it floods all of its ports with the transmission — thereby, defeating the advantage of using a switch. By assigning ports to multicast groups, traffic is reduced to only those ports of interest — thus avoiding needless traffic to devices outside the group.

Static Forwarding Table

Switches maintain tables of station addresses and port assignments. Such tables are continually updated by observing and learning the source addresses found in Ethernet frames. This automatic method can be overwritten by manually entering addresses directly into the address memory — avoiding the periodic "aging" of the address table.

Rapid Spanning Tree Protocol (RSTP)

The Rapid Spanning Tree Protocol (IEEE 802.1w) is a standardized method of creating redundant paths for data transmissions and thereby creating a higher level of reliability. Unlike proprietary fiber ring methods, the RSTP does not require the sole use of fiber and allows additional redundant paths. Recovery time is typically one second or less. RSTP is backward compatible with the older IEEE 802.10 Spanning Tree Protocol (STP) which has, typically, a slower recovery time than RSTP.

OPC Server

OPC is a popular method of exchanging process data in the controls industry. With an OPC server, managed switch data can be served to a compliant human machine interface (HMI) for display with other process data allowing for a neat and unified screen appearance.

Web Server

By having a resident web server in the switch, commissioning of the switch can be accomplished over Ethernet with a standard web browser. This is also a good way of interrogating the switch to ensure proper operation of the network-especially from a remote location.

Internal Temperature Sensor

An advantage of the SNMP Protocol is the ability of the equipment vendor to define a private Management Information Base (MIB) in order to access a special feature of the vendor's product. This is the case of the Internal Temperature Sensor in our managed switches. A management program can access the internal temperature and set a trap if the temperature is too high.

Field-Upgradable Firmware

Contemporary Controls will continually refine its switch products and add features accordingly. Free firmware updates are available at www.CTRLink.com and can be downloaded to devices in the field without charge. Updates to configuration software that runs on workstations are also available for download.