Technical data

Tech Note: Configuring a Modem for an ADR

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Selecting Modems to Use With TOPS and Your ADRs

For long term reliability, be sure to use environmentally rugged modems in the field (such as Peek’s LPM modem.) A

single configuration may not work for all types of modems. With this in mind, it is recommended that you use the same

modems in the central office (for TOPS) and attached to the ADRs in the field. This should result in the highest

percentage of connection rates over time.

Note If a V.90 (56K) modem is used with the central software and a non-V.90 modem

is used in the field, the V.90 feature may have to be disabled in the central

software modem. This is most often accomplished through an S register in the

modem. If this is done, the central software modem will not be able to connect

to any other field modem using V.90.

It is recommended to configure the ADR's “MODEM INITIALIZATION” setting to “HAYES AT” and the

“INITIALIZE MODEM” setting to “BOOT + DAILY”.

Understanding the TOPS-ADR Connection Process

The following steps describe how the connection process between a central-office software package (such as TOPS or

TDP) and an ADR is supposed to work:

1. The central-office software commands its attached modem to dial the phone number for the remote ADR.

2. The remote modem detects the ring and sends the text “RING” to the ADR on the RS232 port. The ADR's modem

cannot answer the call at this point, since the DTR line hasn't been asserted yet.

Note Some modems that go into shutdown do not see the incoming ring unless the

DTR line has been asserted. This results in a Catch-22 situation, as the ADR will

not assert the DTR line until it sees some activity on the RS232 line. The only

way to get around this is to change the “COMMS OPERATION” setting on the

ADR to “ALWAYS ON”. This keeps the ADR com port ON at all times (with

DTR asserted,) but has the side effect of higher power consumption on the ADR.

3. The ADR is woken up by the activity on the RS232 line (“RING”). It then asserts the DTR line.

4. The ADR's modem detects the next ring and can now answer the incoming call.

5. The two modems negotiate and establish a connection.

6. Communications can then take place between the central software application and the ADR through the modem

connection.

7. When communications are completed, the central software sends a command to the ADR to hang up.

8. The ADR de-asserts the DTR line.

9. The ADR modem loses the DTR line and hangs up.

10. The Carrier Detect signal is dropped between the two modems. The modem connection is now terminated.