Terminal and Print Servers -- Traditional Applications
Despite many of the advancements of the computer industry, there still exist a great many applications where serial I/O devices are the best or only solution. Terminal/print/serial servers have long been the best method for networking simple terminals, bar code readers, scanners or printers. Input devices attached to a serial port on a server can reach any host supporting the same protocols as that server. Printers can be shared over the network in the same manner, with a job from one protocol following a job from another. In the case of the print server that has multiple ports, jobs coming from hosts supporting different protocols can even print simultaneously.
Traditionally, terminal/print servers have been larger, multiport devices. But as the marketplace demands that singular devices in remote locations are networked and as technology has developed to allow for single-port device servers to be economically feasible, these smaller servers now provide this remote connectivity. Single port device servers are now being used to provide network connectivity for devices such as bar code readers, factory automation devices, security/monitoring devices and medical devices. This type of technology has been labeled device server technology by industry analysts. For nearly 10 years, Lantronix has been a leader in terminal/print server technology and has been an innovator in the area of micro print server and single-port device server technology. Lantronix is now on the forefront of device server technology for the purpose of networking devices previously not on the network.
For many devices, the only access available to a network manager or programmer is via a serial port. The reason for this is partly historical and partly evolutionary. Historically, Ethernet interfacing has usually been a lengthy development process involving multiple vendor protocols (some of which have been proprietary) and the interpretation of many RFCs. Some vendors felt Ethernet was not necessary for their product which was destined for a centralized computer center - others felt that the development time and expense required to have an Ethernet interface on the product was not justified. From the evolutionary standpoint, the networking infrastructure of many sites has only recently been developed to the point that consistent and perceived stability has been obtained - as users and management have become comfortable with the performance of the network, they now focus on how they can maximize corporate productivity in non-IS capacities.
Device Server™ technology solves this problem by providing an easy and economical way to connect the serial device to the network. Let's use the Lantronix MSS1-T Device Server as an example of how to network a RAID controller serial port. The user (or network manager) simply cables the MSS1-T's serial port to the RAID controller's serial port and attaches the MSS1-T's Ethernet interface to the network. The Lantronix server, once it has been given the necessary configuration information, now makes that serial port a networked port, with its own IP address. The user is now free to connect to the MSS1-T's serial port from a network device (a PC or terminal emulation device) and perform the same commands as if he were a PC directly attached to the controller. Having now become network enabled, the RAID controller can be managed or controlled from anywhere on the network or via the Internet.
The key to network enabling any device is in a server's ability to handle two separate areas: (1) the connection between the serial device and the server and (2) the connection between the server and the network (including other network devices). Terminal, print and serial servers have been developed over the years specifically for the tasks of connecting terminals, printers and modems to the network and making those devices available as networked devices. As current demands for networking other devices increases, these servers need to become more generic in their handling of the attached devices. Additionally, they will have to become even more flexible in the manner in which they provide network connectivity.
Device Server Technology
Dataquest has described a device server to be "a specialized network-based hardware device designed to perform a single or specialized set of functions with client access independent of any operating system or proprietary protocol." Terminal, print and recently one-port terminal servers (Lantronix calls them Device Servers) have come to embody this notion of independence from proprietary protocols and the ability to meet a number of different functions. The RAID controller application discussed above is just one of many applications where these Device Servers can be used to put any device or "thing" on the network. The recent development of the single port Device Server now makes it economically possible to connect even single devices with serial ports to network - prior to this development, users had only multiport solutions which were sometimes too expensive when the serial devices were very far apart.
Someone might ask the question, "But haven't dedicated PCs been used to network some serial devices with success?" The answer to this would be a somewhat qualified yes - qualified because it required the designer of the product with the serial port to have software able to run on the PC and then have that application software allow the PC's networking software to access the application. This task would be somewhat akin to the problems of putting Ethernet on the serial device itself! To be successful, a device server must provide a simple solution for networking a device and allow access to that device as if it were locally available through its serial port. Additionally, the device server should provide for the multitude of connection possibilities that a device may require on both the serial and network sides of a connection. Should the device be connected all the time to a specific host or PC? Are there multiple hosts or network devices that may want or need to connect to the newly-networked serial device? Are there specific requirements for an application which requires the serial device to reject a connection from the network under certain circumstances? The bottom line is a server must have both the flexibility to service a multitude of applications requirements and be able to meet in depth the demands of those applications.
Lantronix Device Servers
Lantronix has been in the terminal, print and serial server technology business for over 10 years. During that time, Lantronix servers have been shipped worldwide and implemented in many different applications. This experience has allowed Lantronix to develop more functionality in our servers that "crosses the boundary" of what many would call traditional terminal or print services. The ability to translate between different protocols to allow non-routable protocols to be routed; the ability to allow management connections to single-port servers while they are processing transactions between their serial port and the network; and the ability to offer a wide variety of options for both serial and network connections including serial tunneling and automatic host connection make these servers some of the most sophisticated Ethernet-enabling devices available today. By virtue of the ability to network almost any serial device, Lantronix has termed our server technology, Device Server Technology.
Let's take a look at a particular example of how Device Servers can be used. Mainframe computers and high-end workstations present a particular management problem in networked environments because they normally reserve a number of critical configuration and management parameters for a serial console port device. The ability to reconfigure system memory, allocate disk resources and build system features are reserved for this console which is assumed to be located in a safe and secure environment (generally a centralized computer room). For the network manager who uses principally networked management tools, the challenge is how does this person manage this type of device? The answer to this question lies in using a universal device server as a console server - by connecting the Device Server's serial port to the console port of the workstation, the network manager can now exercise the full range of console commands from anywhere on the network. The Device Server allows the serial port of the workstation to now become a networked port, reachable via connection to the Device Server's IP address. In this manner, the network manager can connect from any device supporting the IP protocol to the workstation's console port and then can execute the commands normally reserved for that port. The result is that any workstation or mainframe system can therefore be managed over the network as if the network manager were in the central computer room where the console of the system was located.
A user might say at this point that the use of the Device Server in this application is very much like that of the common terminal server. But if one just takes a standard terminal server and puts it in this application, will they be successful? The answer is that they may not. With a console server, you would want to have ways of grabbing a port's attention if it should be hung - this would mean that you would want some kind of comprehensive management function available to you should a connection appear to be faulty. Additionally, you would want some kind of diagnostic information to ascertain if there was network problem or a serial port problem if the connection was not working as expected. Thirdly, the interface to the console might require some special break or control character or even modem signal to be sent to wake up the console or initiate a particular management feature. Lastly, there might be a compatibility requirement with a host-based application program that places severe limitations on how the network connection from the host to the server will take place. The fact is that many of these features may not be available in a standard terminal server and knowing that the lack of any one of them might mean that a particular console could not be networked would lead to a rejection of the proposed server as a solution.
Lantronix engineers have spent the last decade developing the widest possible variety of applications for our server products. One example of this is in the development of our Comm Port Redirector software, a Windows 95/98 and Windows NT program that maps a PC's serial ports to it's network port(s). What this software provides is the ability to take the application software developed for a serial port on a PC and allow that software to be run on a networked PC. That networked PC can now connect to the device attached to the serial port of the Lantronix Device Server as if it were on the PC's serial port. This means that any device with a serial port with a dedicated PC can now become a network device with the ability of a PC anywhere on the network (or the Internet) to manage it. From the start of the network enabling process, there is no need to modify any applications software in the PC to be able to access the Lantronix server's serial port (with serial device attached) from anywhere on the network. This feature is called application transparency.
By virtue of being an independent device on the network, one might think that management of a Device Server might be a problem - nothing could be farther from the truth. As stated before, Lantronix has spent over 10 years perfecting our Ethernet protocol software and Lantronix engineers have provided a wide range of management tools for this device server technology. Since terminal servers and serial servers have serial ports it makes sense that these ports can also be used for management purposes - a simple command set allows easy configuration in this manner. The same command set that can be exercised on the serial port can be used when connecting via telnet to a Lantronix device server. An important feature to remember about the Lantronix telnet management interface is that it can actually be run as a second connection while data is being transferred through the server - this feature allows the user to actually monitor the data traffic on even a single-port server's serial port connection while active. The Lantronix Device Servers also support SNMP, the recognized standard for IP management that is used by many large network for management purposes. And finally, Lantronix has it's own web-based management tool, EZWebCon, a graphical user interface which provides the easiest way to manage the Lantronix Device Servers. In addition to these features, the servers all have Flash ROMs, which can be reprogrammed in the field by download. Many new small device server products do not have this feature. This means that new software might have to be downloaded over the serial port or simply not at all. Lantronix was one of the pioneers of providing software upgrades for free over the Internet and the Lantronix web site (www.lantronix.com) guides the user through the process with ease.
Device Servers - Making the Applications Work
We have looked at why organizations are looking for Device Servers and we have seen one example of it in the area of console service and we described what device server technology should be. But the real test is - does a device server provide all of the features required to network enable the application successfully? We are going to look at a few applications areas in which there is a great deal of interest in device server technology and how Lantronix Device Servers facilitate those applications.
Microprocessors have made their way into almost all aspects of human life, from automobiles to appliances to even hockey pucks. With so much information out there to be gathered, it stands to reason that an organization or individual will want to collect as much of it as fast as possible. Although some data acquisition devices use a serial interface, there are a wide variety of other interfaces to support these devices. One such standard is RS-485. Designed to allow for multiple devices to be linked by a multidrop network of RS-485 serial devices, this standard also had the benefit of greater distance than offered by the RS-232/RS-423 and RS-422 standards. Many of these applications run in campus-type environments, so right-of-way to lay cable between devices was available.
Because of the factors we have previously outlined, these types of devices can benefit from being network enabled. Firstly, Ethernet networks have a further range than many serial technologies. Secondly, Ethernet protocols actually monitor packet traffic and will indicate when packets are being lost compared to serial technologies which do not guarantee data integrity. Lantronix's full family of Device Server products provides the full gamut of support required for network enabling different serial interfaces. In particular, the MSS485-T serial servers support RS-485 and allow for easy integration of these types of devices into the network umbrella. For RS-232 or RS-423 serial devices, the MSS1 and MSS100 products can be used to connect sensors to either Ethernet or Fast Ethernet. The Lantronix terminal server products offer multiport configurations for those sites where multiple sensors may be in close proximity.
But this is just the beginning of the support that may be required for critical applications. Say that a number of data acquisition devices monitor the temperature of a furnace - it stands to reason that any prudent user would want to ensure themselves of making sure these sensors are always working and working correctly. The answer here is that Lantronix's universal device servers have several features that enable this application to work efficiently and correctly. To verify that a sensor and its server is transmitting, a user could set up a ping application using the IP protocol to sound that unit every second or so - this would validate the existence and operational capability of the data device. Still using IP, the Lantronix device server could be programmed to transmit data to separate IP addresses on the network for cross-checking or validation at different management stations. These features, standard to Lantronix device servers, may not be found on other products being offered for data acquisition applications.
Factory Floor Automation
For factories that are running automated assembly and manufacturing applications, time is money. For every minute a device is idle, productivity will decrease. Many automated factory floor devices have either serial ports or require a dedicated PC to program them. In some cases, handheld PCs are used to reprogram devices for different functions. These devices could be networked to allow them to be reprogrammed over the network, saving time and money. From a central location or actually from anywhere in the world with network connectivity, new device programs can be downloaded.
One item of interest is how that input programming is formatted. We have reviewed how the Lantronix device servers have a comm port redirector software package to provide application transparency, but since many of these automation devices are legacy or proprietary, any number of different data streams could be used. Lantronix device servers have the ability to set up their serial ports for virtually any kind of data transaction. In the IP environment, this includes the ability to support telnet connects or telnet connects without IAC negotiation (raw sockets). Additionally, all Lantronix device servers can support binary character transmissions. In these situations, the need for possible flow control may arise and Lantronix has accounted for this need by supporting RTS/CTS flow control on our DB25 and RJ45 ports. So be it a simple ASCII command file or complex binary program that needs to be transmitted to a device, Lantronix device servers can do the job.
One area that every organization is concerned about is security. Card readers are commonplace now and these type of devices are good candidates for device server technology - when networked to a central system, there will be records of all access within the organization. Newer technology includes badges that can be scanned from a distance of up to several feet and biometric scanning devices that can identify an individual by a thumbprint or handprint. device servers allow these types of devices to be placed throughout an organization's network and allow them to be effectively managed by a minimum staff at a central location.
One more area of security systems that has made great strides is in the area of security cameras. In some cases, local municipalities are now requesting that they get visual proof of a security breach before they will send authorities. Lantronix device server technology provides the user with a host of options for how such data can be handled. One option is to have an open data pipe on a security camera - this allows all data to be viewed as it comes across from the camera. The device server can be configured so that immediately on powerup the serial port attached to the camera will be connected to a dedicated host system. Another option is to have the camera transmit only when it has data to send. By configuring the device server to automatically connect to a particular site when a character first hits the buffer, data will be transmitted only when it is available. One last option is available when using the IP protocol - Lantronix device servers can be configured to transmit data from one serial device to multiple IP addresses for various recording or archival concerns. Lantronix device server technology gives the user many options for tuning the device to meet the specific needs of their application.
Scanning devices such as bar code readers or debit card scanners are another application where device server technology can be effectively applied. When a bar code reader is located in a remote corner of the warehouse at a receiving dock, a single-port server can link the reader to the network and provide up-to-the-minute inventory information. A debit card scanner system can be set up at any educational, commercial or industrial site with automatic debiting per employee for activities, meals and purchases. A popular amusement park in the United States utilizes such a system to deter theft or reselling of partially-used admission tickets - by having no distinguishing marks other than the person's name and a barcode on the card, the black market for partially-used tickets has been greatly reduced.
Lantronix's device server technology simplifies these types of applications with a feature called autostart. Once the reader or scanner is powered on, it will remain on permanently for a predetermined length of time, the device server to which the serial port of the reader/scanner is attached will automatically open a connection to a specified host upon powerup of the unit. This connection will remain open as long as the user wishes, capable of supporting any amount of continuous transactions. If the attached scanner is one which is only going to be used for a short period of time, then the Lantronix device server can be configured for both preferred connection and dsrlogout - this combination will terminate a connection when the attached scanner device is turned off but still retain the ability to make an automatic connection to the specified host when the scanner begins operations again.
Medical devices are another area where device server technology can provide great flexibility and convenience. Many medical organizations now run comprehensive applications developed specifically for their particular area of expertise. For instance, a group specializing in orthopedics may have x-ray and lab facilities onsite to save time and customer effort in obtaining test results - connecting all the input terminals, lab devices, x-ray machines and developing equipment together allows for efficient and effective service. As many of the more technical devices previously relied upon serial communication or worse yet, processing being done locally on a PC, then so device server technology can be used to link them all together into one seamless application. Of course, Internet connection allows the physicians to take advantage of any new information relevant to their pursuits.
Larger medical labs, where there are hundreds of different devices available for providing test data, can greatly reduce their workload by using device server technology to replace dedicated PCs at each device. At first glance, this might seem like a tradeoff given the cost of a device server and the cost of a PC - but think not of the hardware alone, think of the man-hours required to create software that would allow a PC-serial-port-based applications program to be converted into a program linking that information to the PC's network port. A Lantronix device server can resolve this issue by allowing the original applications software to be run on a networked PC and then use the Lantronix Comm Port Redirector software to connect up to that device via the network. Where originally, there was a PC at each device and software development required to network that data, now there is only a couple of high-end networked PCs doing the processing for all of the devices.
So Many More Applications
There obviously are many more applications where device server technology can be used - some as mundane as vending machines' inventory monitoring and others as critical as rocket launch pad telemetry data collection. The point is the move is on to migrate as many things as possible on the network. As we have also seen, applications support may require more than just simply getting an IP address for a device - it may require special handling of the flow control or data characteristics of the serial port, it may require special processing during the transfer to the network and it may require special management abilities far beyond a simple telnet capability. Lantronix has been an industry leader for over a decade in the terminal, print and serial server business and as these applications-specific servers are being called, device servers. Examine the Lantronix products that you can find by choosing 'Lantronix Products' below and you will find products that will both meet and exceed your applications requirements in both performance and price.