Data communications networks are a relatively new technological development, but the obvious power of the concept has resulted in an explosion of different networks for various purposes that number in the thousands. Many of these are proprietary and specialized, often applied for no more than a few hundred nodes if that. Still, even counting only the more common network protocols, the variety is overwhelming and presents some serious challenges to users who often have technical and performance concerns that mandate the integration of two essentially incompatible networks.
Various solutions exist including some good custom-designed interfaces, but in general the exercise has been characterized as frustrating, expensive and/or technically inadequate. S-S Technologies' involvement began with its Direct-Link product line of network interface cards which were often being applied in gateway installations. It occurred to our research and development team that what was needed was a high-performance, cost-effective, intuitive and very flexible system for generating gateways between virtually any network combination being encountered by users and system integrators charged with coming up with a effective solutions. After considerable development and field-testing, the X-Link Gateway Engine was born; a high-performance hardware platform married to a unique software architecture that featured interchangeable drivers for various network protocols. Intuitive configuration software allows the user to simply select two applicable drivers from a growing library to create an instant gateway. Powerful data-mapping features insure efficient network traffic and optimal speed.
The X-Link has subsequently found an impressive spectrum of applications in a wide array of industries ranging from mining to food processing and public utilities. It has been adopted by a number of high profile control, machinery and software vendors as a standard gateway solution for their products, insuring them of an unrestricted market access where communications obstacles had previously been a problem.
In spite of the initial success of the X-Link Gateway Engine, there are still many who are unfamiliar with the concept of network gateways and/or the X-Link Gateway Engine Solution. The following are a number of frequently-asked-questions about X-Link and gateway applications generally.
X-Link is comprised of both elements. X-Link software uses a special multi-tasking operating system and real-time messaging kernel. To function successfully, it must have full control of the computer platform it is operating on. The X-Link CPU is provided to reduce costs to the user by eliminating all but the most essential elements of the CPU, and to insure a consistent performance that cannot be guaranteed with commercially available, standard PCs. This is not an uncommon practice and most networking companies will insist on full control of the equipment specification in order to guarantee the performance of their software (i.e. Novell). By providing both the hardware and software in a single package, S-S Technologies reduces the costs of the solution and insures a high level of performance.
X-Link includes everything you need to implement a gateway with exception of interface cards, of which you may need one or more. The interface cards allow the X-Link to communicate over the networks. Some networks use standard mediums like RS-232, RS-422 or RS-485. X-Link has a built-in port that can be used in these cases without the necessity of purchasing a serial network interface card.
The purchase of an X-Link entitles the user to full access to our library of network protocol drivers without additional charge. Some exceptions may occur with third-party or custom-developed drivers for proprietary networks.
Without knowing the specifics of your gateway configuration and the performance of each network to which the X-Link is connected, it is virtually impossible to provide a meaningful answer. In most cases, one of the two networks is slower that the other. Further latencies can be introduced by the PLC, MMI, problems with the bus or connections. X-Link performance may also vary according to the number of mappings it must resolve. In general terms, the X-Link operation can be described as transparent since it is almost always the fastest component in the system (500% faster than a PLC-5).
Yes it can . Control operations generally require a certain speed threshold, deterministic operation, and reliable data transport. X-Link has the inherent speed necessary for all but the most demanding control operations and supports a number of deterministic protocols (A-B Remote I/O, Profibus DP, Reliance Rail I/O, Modicon Remote I/O, etc…) specifically designed for control-type applications.
The following versions of X-Link are CE marked:
X-Link appears as a native node on whichever network it resides. On an Allen-Bradley network, X-Link would appear as a PLC (several emulations to choose from) or as a rack of I/O. The same is true for other industrial control networks as well. Data destined for another network is addressed to an emulated register on the X-Link that is consistent with the prevailing addressing scheme (e.g. N7:0, etc…). That emulated register is mapped in the X-Link to a destination or multiple destinations on another network. X-Link can also actively poll data on a network, again using the native addressing scheme.
X-Link has a number of polling options that allow the user to minimize the data traffic. For the source data, X-Link can query in adjustable intervals, poll when requested by the companion driver (network) or poll when stale (data has not be refreshed within a specified interval…). Updating data can also be done with adjustable interval or periodic polling as well as updating when prompted by the companion driver or when the data has changed. The combination of these polling methods results in a large variety of efficient data transfer strategies. (See X-Link User Reference Manual for more information) Some customers have used X-Link to relieve network overloading by using the polling options for maximum effect.
It is important to understand the difference between protocols and networks. X-Link only transfers data between two protocols, however in some cases, drivers may support multiple networks using the same protocol. An example of this would be Modbus which can support up to four Modbus networks simultaneously, transferring data from these networks to one other. Please refer to the X-Link driver list for information about multi-port drivers.
X-Link does not require programming. The user interfaces to the X-Link from a PC running X-Link configuration software through a serial cable connected to the configuration port of the X-Link. After having installed the appropriate network interface cards, the User downloads the kernel and two drivers from the library that correspond to the target networks. Once configured, a gateway is created. The user then maps data from the source to the destination(s) using a fill-in-the-blank process that is faithful to the context and syntax of the respective networks. Thus, integer data, N7:0, Station 5 (PLC-5) may be a source on Data Highway Plus and the Status channel, offset 0, Drop 3 may be the destination on Modbus.