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done the same way as making an ordinary call.
A so called `maintenance terminal' can be used to change convertor settings. This terminal
must be able to make an ordinary call to an individual convertor in order to change the modem
settings. A maintenance terminal is for example a SOPHO-SET S375D with a terminal
connected to it.
V.24
DCE
MAINTENANCE
TERMINAL
DCE-SOPHO-SET,
SOPHO-LAM or LAM
1
2B+D,( B=64kbps, user channel.
2
SOPHO-LAM P375 release 3 in DTE mode (!)
3
Special cable (See appendix C)
4
Modulated carrier.
Figure 3-5 Example of a Maintenance Terminal connection (Leased Line).
In case of a leased line configuration only the modem settings can be changed using a
maintenance terminal, NOT the SOPHO-LAM settings. The reason for this is that the
maintenance terminal has access to the V.24 interface of the modem, from the SOPHO-LAM
towards the modem and not the other way around. So, for example, the modem settings can
be changed by using Hayes commands (this depends on the modem used).
In order to change the settings of the SOPHO-LAM the maintenance terminal must have acces
to the V.24 interface of the SOPHO-LAM, from the modem towards the SOPHO-LAM. This
is not the case in the leased line configuration. Therefore in the leased line configuration the
maintenance terminal can not be used to change the SOPHO-LAM settings. Another method
has to be used. For example by using the key pad of the SOPHO-LAM or by downloading the
SOPHO-LAM.
To change the modem settings, the maintenance engineer has to dial the convertor DNR.
After dialling this DNR the connection is made between the maintenance terminal and the
individual convertor. When the modem supports Hayes commands, the modem settings can
be changed using Hayes commands.
Normally users are not allowed to dial individual convertors. To prevent that users can dial
1
SN
IMP
64 kbps
2B+D
DLC/
DTX-I
1
IMP
64 kbps
2B+D
DLC/
SOPHO-
DTX
MODEM
2
3
V.24
LAM
4
Analogue
Trunk
line
33
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