Operation
RFI-9256 Radio Modem User Manual
Page 36 of 109
DTR CONTROL OF HAYES STATE
The Data Terminal Ready (DTR) input to the radio can be used to control the Hayes dial-up state.
Ignore DTR:
The radio does not use the DTR signal to control its connection state.
Hang-up on DTR Low:
The radio will hang-up whenever the DTR line is low. If this option is
selected, and DTR is low when a remote radio is dialled then the connection will be terminated the
moment after it is established.
Hang-up on DTR Dropped:
The radio will hang-up whenever DTR changes from high to low.
Local on DTR Low:
Whenever DTR goes low, the radio will enter local command state. This is the
same as entering the escape sequence.
DIAL-UP NETWORKING WITH BACK-TO-BACK REPEATERS
A Hayes dial-up network can be extended by one or more back-to-back repeaters. In order to establish a dial-
up connection through a back-to-back repeater, an extension to the dialling system is used:
ATD<repeater
0
><repeater
1
>...<repeater
n
><address><extension><CR>
The address of each repeater to dial through is prefixed before the address of the destination radio and
extension. Thus to dial the auxiliary port of the radio with address 2200 first through repeater 10 and then
through repeater 43 the following dial string would be used:
ATD1043220001<CR>
In order to access the repeater slave’s terminal menu, dial up the menu system as if it were any other slave.
In order to access the repeater master’s terminal menu dial up the main port of the slave (the port that has
been connected through to the master unit), then use the master units AT command interface to bring up the
menu system via the
AT?
command.
When using back-to-back repeaters in dial-up networks, there are a number of rules that must be observed:
The protocol mode needs to be set as “Dialup Repeater” via the “Radio Configuration Menu”.
The escape character on the repeater master and repeater slave must be set to ‘-‘.
The escape guard time on the repeater master and repeater slave must be set to 200ms.
The main port DTR mode on both the repeater master and repeater slave must be set to “Hang-up
on DTR dropped”.
The local address of the repeater slave and repeater master must both be the same, and must both be
in the range 10-99.
The local address of all non-repeater units must be in the range 1000-9999.
The DTR line is used in the back-to-back repeater wiring harness in order to propagate Hayes hang-up
requests through the network. If this line is not connected there is a possibility that the hang-up request could
get lost and the repeater network lock-up, believing there to be an established connection.
For this reason it is not advised to use dial-up networking through back-to-back repeaters on the auxiliary
port.
