ATO CMM 900-3W manual What is the flow control method recommended?

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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.

 

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Contents CMM 900-3W User Guide Frequently Asked Questions FAQ Table of ContentsFeatures Product Overview∙ Requires 5 Volts DC @ 1500 ma Applications Serial Port Pins RS 232 interfaceYour package includes Specifications Modem Setup and RegistrationWhat you need to provide Registering the Cellular Modem UnitDIP Switch Settings Starting and Configuring the ModemInitializing the Cellular Modem Using the Cellular Modem to Communicate Activating the Cellular ModemCommand State Theory of OperationPage Result Codes Transitioning Online State à Command State On-line StateSupported AT Commands AT Commands common to all modesNon-volatile memory of the cell-modem Troubleshooting What is the flow control method recommended? Yes