Services and Protocols

MicroTelnet Services and Protocols
TelnetPro supports a variety of internet protocols and services.

Address Resolution Protocol ARP
MicroTelnet uses ARP to convert a remote IP address to a MAC address so it can send packets directly to the remote device.

PING
MicroTelnet will also respond to ping request. You can check that MicroTelnet is connected to the network by pinging its IP address. Most operating systems have a ping command. For Windows you can issue the command at the DOS prompt of COMMAND.COM. Under Mac OS X, you issue the command in a terminal window.

In Unix you can issue the command in any shell. Here is a sample output from a ping command under windows:

Zero Configuration (ZeroConf) Link Local (LL) Address Acquisition
MicroTelnet conforms to the IETF draft with specifies how a host may automatically configure an interface with an IPv4 address within the 169.254/16 prefix. This means that MicroTelnet can automatically configure itself with a unique IP address. This IP address, however, is only usable on the local link, which means that it is not routable outside the local link. So a MicroTelnet using only a Link Local address can only communicate with devices which are on the same physical network. If you need MicroTelnet to access or be accessed by devices outside of the local network, you will need to make sure DHCP is enabled or assign MicroTelnet a unique static IP address

Multicast DNS (mDNS)
MicroTelnet conforms to the IETF draft cheshire-dnsext-multicastdns-04 which states “Multicast DNS (mDNS) provides the ability to do DNS-like operations on the local link in the absence of any conventional unicast DNS server. In addition, mDNS designates a portion of the DNS namespace to be free for local use, without the need to pay any annual fee, and without the need to set up delegations or otherwise configure a conventional DNS server to answer for those names. The primary benefits of mDNS names are that (i) they require little or no administration or configuration to set them up, (ii) they work when no infrastructure is present, and (iii) they work during infrastructure failures. “
MicroTelnet uses mDNS to advertise its name and the services it has available.

Rendezvous
The combination of ZeroConf LL and mDNS allows MicroTelnet services to be browsable by Rendezvous browsers. Rendezvous is an Apple trademark which “enables automatic discovery of computers, devices, and services on IP networks. Also known as Zero Configuration networking, Rendezvous uses industry standard IP protocols to allow devices to automatically find each other without the need to enter IP addresses or configure DNS servers.
Rendezvous is an open protocol, which Apple has submitted to the IETF as part of the ongoing standards-creation process.”

Dynamic Host Configuration Protocol (DHCP)
MicroTelnet uses DHCP in the presence of a DHCP server to configure its IP address, gateway and network mask.

Transmission Control Protocol / Internet Protocol (TCP/IP)
TCP/IP is the core communications protocol that MicroTelnet uses to communicate reliably on the network.

User Datagram Protocol (UDP)
UDP is used by such things as mDNS and the MicroTelnet UDP serial protocol. UDP is not a reliable protocol and thus data sent with UDP is not guaranteed to arrive at its destination. If you use UDP to communicate with MicroTelnet, you will need to take this into account.

Hypertext Transfer Protocol (HTTP)
HTTP is the web protocol which is used to communicate with MicroTelnet’s web server. MicroTelnet’s web server is primarily used to display and set MicroTelnet’s configuration.

Telnet
This service is used to pass data between a network connection and MicroTelnet’s serial port. The default TCP/IP port for Telnet is 23. The easiest way to attach to MicroTelnet’s serial port is to issue a telnet command. For example, telnet 192.168.2.7 Characters typed into the Telnet program are sent to MicroTelnet. Characters that MicroTelnet receives are sent to the Telnet program.
MicroTelnet currently only operates in binary mode. This means that it passes all characters unchanged back and forth through the Telnet port.

Daytime
This service is used to get the elapsed time that MicroTelnet has been running. To get the elapsed time, you need to open a TCP/IP connection to MicroTelnet on port 13 and read the data from that port. The easiest way to do this is to run the telnet program with port 13. For example, telnet 192.168.2.7 13

Discard
This service throws away any TCP/IP data that is sent to it. This is used mostly for speed testing. The default port for discard is 9.

UDP Serial (UDPS)
This is a MicroTelnet specific protocol which uses UDP to send and receive serial data. UDPS is a specialized protocol. Data that is received by MicroTelnet’s serial port is transmitted using UDP and the default port of 10001. MicroTelnet can be configured to either accept UDPS data from only a specific computer or the first computer that sends it UDPS data. If configured for a specific computer, MicroTelnet can send data at any time to that computer. If configured for the first computer that sends it data, then MicroTelnet has to wait to receive data so it can determine the response IP address.
UDPS is useful in a polling environment where a master computer polls multiple slaves for data. The master computer would send a data packet which elicits a response from the device attached to MicroTelnet. The data would then be sent to the master computer.

End Plate Description

The MicroTelnet Telnet box has two end plates which contain three connectors, an LED indicator and a reset button.

The DB-9 Connector is a male RS232C DTE connector. This means that it is electrically identical to a PC serial port connector. The signals available on the connector are

The Recessed Reset Button is used to reset MicroTelnet to its factory default state. See the Performing Hardware Reset to Set MicroTelnet to Factory Defaults section on how to operate the button.

The Blue LED Indicator has multiple functions

• During normal operation it indicates that the link is active. It stays constantly lit on an active link.

• When MicroTelnet is being reprogrammed the LED will flash indicate that the internal flash is being erased and reprogrammed. This will happen when new Firmware or Website is software is loaded or when the hardware reset button is pressed.

The Ethernet 10BaseT RJ45 Connector is used to connect to the Ethernet network.

The Power Connector supplies 7.5VDC to power MicroTelnet. The power connector label states 300ma. This is the maximum power that MicroTelnet is rated for, although it typically consumes less than 150ma.

Module PinOut:

The Telnet module consists of a circuit board with a dual-row 18-pin header. Pin 1 is identified