Siemens MC55 User Manual download pdf (Page 16)

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The GPRS GSM wireless modem module

The GPRS6055 wireless E-GPRS/GSM modem is built around the Siemens MC55 tri-band

900/1800/1900 MHz GPRS cellular engine. It is designed both for handling complex industrial

applications such as telemetry, telematics or communication, and for integration in stationary or

mobile fields all over the world. General information on this product is available at

www.siemens.com

The GPRS6055 is capable of powerful communication using GSM data interfacing. GPRS data

rates can reach up to 85.6 kbit/s max downlink depending on the network capacity and the

network load. Engineers must take into account that GPRS data rates will vary dynamically

depending on network conditions. This must be considered when designing software and system

specifications. Roaming agreements and GPRS data support may not in all cases be available

when moving from country to country. Check with your local network provider for GPRS

coverage.

The GPRS6055ER is capable of FAX and standard SMS text messages. The data terminal rate is

9600 baud for all host commands (AT commands). The GPRS6055ER modem module antenna

interface connector uses an MCX connector. The mating antenna connectors and cables are

supplied by RTD.

GPRS/GSM wireless modem module interfaces

The GPRS6055 GPRS/GSM modem is connected to the host computer through a dedicated ISA

serial port. The default configuration for the GSM serial ports is:

GSM Interface

• 9600 baud

• 8 data bits

• No parity

• 1 stop bit

GSM Antenna considerations

Typically standard GSM antennas use a female FME connector. This connector needs an

adapter unit before it can be connected to the GPRS6055ER.

RTD recommends the use of high quality antennas with the GPRS6055ER. We have tested

successfully with antennas from Hirschmann Rheinmetall Elektronik.

Visit http://www.hirschmann.de/

for information on GSM antennae.

A very useful AT command that shows quality of the signal reception is: AT+CSQ. The format of

the response is AT+CSQ: received signal strength, bit error rate. The received signal strength

shows the quality of the network signal and ranges from 0 to 31 as shown in the table below. A

value of greater than 10 should give an acceptable connection. The bit error rate number will

range between 0 and 7.

Received Signal Strength Values (99 = undetectable signal)

0 - 113 dBm 8 - 97 dBm 16 - 81 dBm 24 - 65 dBm

1 - 111 dBm 9 - 95 dBm 17 - 79 dBm 25 - 63 dBm

1 2 ... 11 12 13 14 15 16 17 18 19 20 21 ... 30 31

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Siemens MC55 User Manual Page 16