ATO CMM 900-3W, Руководство пользователя

Страница: 16 / 18

Page 16 of 16
8. FREQUENTLY ASKED QUESTIONS (FAQ)
Q1: What is the flow control method recommended?
A1: If the host is a PC, Hardware flow control is recommended.
However, in most control instrumentation, either software or no flow control is
called for.
Q2: How do I disable any flow control?
A2: Simply disable both the Hardware and software control switch settings. This is
not recommended for large file transfers.
Q3:
I need to connect the Cellular Data Link to a machine, which does not
understand your messages. All it needs is data. Which configuration is
recommended?
A3: Please use the ATQ1&w&w1<CR> command.
Q4: Have you experienced unreliable communication with certain modems?
A4: Yes. Several generic brands tend to throw hot signals (i.e. strong signal levels)
on the line. This causes the cellular service to over-modulate, which leads to
distortions and results in unreliable connections.
Q5: What is the solution?
A5: We recommend that you use modems that support MNP-10 and also allow
transmit level to be reduced to between –15 dbm
à
–20 dbm. Rockwell based
modem designs generally meet these requirements.
For Rockwell based modems, please try the following commands
on the land line modem:
•
AT-SEC=1,18 <CR>. This will enable MNP 10 and set transmits level to
–18 dbm.
•
AT+MS=11,1,1200,2400X3&W&W1<CR>. Sets the modem to
communicate between 1200 and 2400 bps.
Q6:
Is there any simple way to avoid frequent loss of connection?
A6: Please program the CMM 900-3W as follows
AT+MS=11,1,1200,1200&W&W1<CR>
This will force the CMM 900-3W to connect only at 1200 bps.
Q7: What initialization string is recommended to communicate with non-MNP
modems?
A7: Connection with non-MNP landline modems is not recommended.