4.4 Data Connection Using USB Port

EasyGate device is equipped with virtual serial port that simulates standard COM port in PC according to specification RS-232C. Installation is described in section 3.1 paragraph „Installation and setting of EasyGate PCManager" points 1 to 3.

The transmission rate ranges from 1200 to 115200 bps (EasyGate supports autobauding, i.e. responds to an AT command at a rate identical with the AT command transmission rate, and retains set on this rate). The transmission setup must be 8 bits, no parity and one STOP bit (8N1).

During the call establishing and terminating the serial interface of GSM module is used by the central processor of EasyGate. During this time periods the communication with module is impossible. The communication is blocked by setting of the signals for flow control on virtual COM port. All PC SW must provide transmission hardware flow control (HW handshaking).

CSD PC-PC Data Transmission

The CSD mode provides data transmission in the GSM network at the maximum transmission rate of 14400 bps. It works like a classic connection of two modems (AT commands ATD, ATH, ATA, etc.). Connection can be made with another GSM modem or a PSTN modem.

Caution

  • Data calls and fax calls from the PSTN come as voice calls (the telephone line on EasyGate rings) because an analog network is unable to distinguish a modem/fax call. Therefore, it is necessary to have a special telephone number for incoming data and fax calls on the SIM card different from voice call numbers (Multi-numbering scheme). The GSM network identifies a call incoming to this number as a data/fax call and lets the COM serial interface ring.

USB driver instalation

For communication over USB port of EasyGate is necessary to install USB driver. The installation is usually automatic after connection to USB port by delivered USB cable. The connection is described in detail in part 3.1 – “Installation and setting of  EasyGate PCManager”.

Internet connection

You can use the provider’s installation wizard in case it supports the module used in gateway (Cinterion MC55i-w for GSM version, Simcom SIM5320E (A, J) or PHS8-P for UMTS version). When this wizard is not available, you have to use manual setting according following instructions.

Module driver installation

For communication using module is necessary to install modem driver from CD-ROM Easy Gate.

Driver for MC55i-w on CD is named: ‘mdm2n_vx.x.inf,x’ (x – driver version).

Drivers for SIM5320 and PHS8-P are available for 32 and 64 bits Windows systems, they are placed in appropriate directories.

APN setting

For internet connection is necessary to set the APN of your mobile provider. It could be set in gateway using PCManager (GSM&SIM - GPRS APN) or  in modem extra settings in PC:

Example:  at+cgdcont=1,"IP","internet.t-mobile.cz"

APN name must be received from your mobile provider, in example is the APN of      T-Mobile Czech republic used.

Network connection setting

  • Ask you mobile provider for Internet connection instructions because they can be different for each provider (especially the telephone number to be dialed, eventually Username, Keyword, DNS, etc.). Set phone connection in your PC using Network connection setting and select appropriate modem. Set the connection parameters (Username, Password, Dial number) according to information from your mobile provider (obviously Username ‘internet’, Keyword is empty an Dial number *99***1#). Finally use button ‘Dial’ to establish connection to internet.

Caution

  • Mobile providers mostly specify the *99# number to be dialed for GPRS connection in their instructions. Cinterion GSM modules require the *99***1# format.

Data connection – CSD or GPRS and other technologies?

CSD connection is used for data connection of two endpoints, similary as the data connection of two modems in fixed network. The maximum CSD transmission rate is 14400 bps. GSM connection is reserved for the whole time of connection and calls are charged according to the connection time. The CSD mode can provide data connection of two PCs.

GPRS connection (for GSM version) or EDGE, WCDMA and HSDPA connection can’t be used for direct connection of two devices. It is dedicated for connection to APN, usually to internet. Most mobile providers charge the connection according according to the volume of data transmitted or by a lump sum and so the GPRS is suitable for long-time connection.

SMS Sending and Receiving

It is possible to send and receive SMS units using appropriate AT commands. There are a number of PC programs that are based on this principle. For GSM version install SW supporting Cinterion modules (Siemens mobile telephone SW can also be used), for UMTS version install SW supporting modules Simcom or Gemalto. You can send and receive SMS even during EasyGate voice calls.

Combination of serial connection with Voice Calls

As already mentioned, SMS transmission can be made even during telephone calls. The SMS program is only blocked temporarily during outgoing call establishing and incoming call ringing.

The same applies to PCManager monitoring. A message announcing that EasyGate is blocked is displayed during voice call establishing.

No voice call can be made during CSD data connection.

Outgoing and incoming calls can be made during GPRS connection. The GPRS connection remains active during the whole call but no data can be transmitted (EasyGate is a GPRS terminal of class B). Once the call is terminated, data transmission is recovered immediately. Data connections Edge, WCDMA and HSPA on UMTS version of Easy Gate can be active concurrently with the voice call.

List of Supported AT Commands

There are original files related to Cinterion GSM modules and Simcom UMTS modules in the PDF format on the EasyGate CD-ROM.

Caution

  • Since the GSM (UMTS) module is primarily used by the EasyGate central processor for voice calls, use AT commands carefully. You might establish wrong configuration of the module thus making EasyGate inoperative. To solve most of these problems, switch EasyGate off and on again to make the central processor execute full initialization of the module.

Do not use particularly:

ATQ1

AT+CMUT=

AT^SNFI=

ATS3=

AT+CMUX=

AT^SNFM=

ATS4=

AT+CSCS=

AT^SNFO=

ATS5=

AT^SAIC=

AT^SNFPT=

ATV0

AT^SM20=

AT^SNFS=

AT&C0

AT^SMSO=

AT^SNFV=

AT+IPR=

AT^SNFA=

AT^SNFW=

AT+CFUN=

AT^SNFD=