Data Engine Ports

In the JNOS40 attach command, the radio ports in the Data Engine are named (numbered) 2, and 3.

2 is internal port A, and

3 is internal port B.

You may still give a mnemonic name to each port; the numbers are equivalent to the port addresses in the JNOS attach commands so that the program knows which port you want to use.

NOTE: port B is simplex only !

The modem type installed in each internal port is automatically sensed when the port is 'attached'.

Attaching the internal radio ports.

Syntax is:

'attach 2|3 name mtu speed [f][n]'

where:

name - is the interface name

mtu - is the maximum transmission unit.
MTU is tested against interrupt buffer size when
the ports are attached. If MTU is too large,
an error message will result and the 'attach'
will be aborted. See below.

speed - is the radio speed.

[f][n] - are optional parameters. f indicates full duplex and n is the value written to the mode AUX pins. If both are used, f should lead n !(This is used in the Kantronics 1200Bd modem to choose the type of CD circuitry to be used.

n = 0 (DEFAULT) is sine wave detection as DCD

n = 1 is the signal from the 3105 modem chip as DCD

n = 2 is the external cd signal as DCD )

Examples:

	attach 2 port2 256 1200 2		
attach 3 port2 768 2400 f1		
attach 2 port2 1024 9600 f

Modem types A,B and D have been tested by WG7J. Type D (the simple loop back for testing) is set to full duplex always, and can NOT (yet) be used in port B. Type C modems (TAPR K9NG, etc.) have not been tested, but might work.

Note: with the type B modem, the speed parameter is a "don't care" value since both rx and tx are externally clocked. The value for speed will show up in the 'ports' display though.

HINT: If you have a DE1200 modem that you might want to replace with a DE9600 modem in the future, and don't want to have to reburn eproms, or if you want to change the modems to opposite slots or whatever, consider the following:

With the type B modem (i.e. DE9600) the speed parameter is ignored. You may enter a value of 1200 which will not hurt anything while a Type B modem is used. Later you may plug in a DE1200, modem, type A will be sensed, and the speed correctly set to 1200Bd! The only problem with this approach is that optimal MTU for higher speeds is usually larger than values useable for 1200 Bd.

The TXTAIL is automatically set to 4 characters at the radio port speed which at 1200 Bd amounts to 26ms. If you attach the ports with the 1200bd set as shown above, the 'param <iface>' command will always show txtail to be 26ms, since this is calculated from the port speed given. However, if you plug in a 9600/19200 baud modem, this calculation will be in error. The actual txtail then is about 3ms or 1.5 ms, respectively.

If you always will be using DE1200 and DE9600 modems, you should attach them as:

	attach 2 port2 256 1200

Port Descriptions

You can give each port a short description that will be displayed when users type the 'P' command at the node.

ifconfig port1 de "144.92 MHz local lan port"

ifconfig port2 de "223.42 MHz cluster port"

ifconfig port3 de "430MHz 19200Bd link to Eugene"