Reception and transmission of data via csd channel. Preparing iRZ modems for operation using CSD technology using a terminal program. Is it possible to connect M2M Monitoring yourself?

All RX series modems are configured by default for data transmission mode via the CSD protocol.

First, let's take a look at what CSD is and why modems operate in this mode by default.

1. What is CSD?

Let's refer to Wiki for information:

Circuit Switched Data(CSD) is a data transmission technology developed for mobile phones GSM standard.

CSD uses a single time slot to transmit data at 9.6 kbps to the Network and Switching Subsystem NSS, where it can be transmitted through the equivalent of a normal modem connection to the telephone network.

A CSD call works very similar to a regular voice call on GSM networks. A single time interval is allocated between the phone and the base station.

Data transmission on GSM networks has been improved since the introduction of CSD. Since the maximum data rate for a single time slot is 9.6 kbit/s, many operators allocate two or more time slots for CSD calls.

To work with this technology, you need to order a connection to the CSD service from your mobile operator (if this service is not already connected).

In most cases, the CSD service is disabled by default.

We can draw up a principle of interaction [program<=>modem<=>modem<=>device]

Those. the program begins to send AT commands to the modem interface port, the modem, in turn, with its SIM cards, makes a voice call to the phone number of a SIM card installed in another modem.

The remote modem answers the call.

This creates a communication channel between the two modems, through which we can send or receive any data.

2. Equipment survey via CSD

To understand how gaining access to a meter or some other equipment works, to configure it or read readings, let’s look at a simple example:

Counter polling Mercury 230 ART-01 PQRSIN using two modems TELEOFIS RX101-R4 and TELEOFIS RX108-R4

Initial data:

Counter Mercury 230

The RX101-R4 modem has a USB-B interface for connecting to a PC, so it will be a calling modem.

The RX108-R4 modem has an RS485 interface and is connected to the Mercury 230 meter, so it will be a Receiving modem.

Two SIM cards with a positive balance and activated CSD service

Software Universal configurator of Mercury meters, for connecting to the meter: Download the configurator

Let's define the connection diagram:

Let's connect our modems according to the diagram below.

For RX101-R4, install drivers on the PC (Only drivers, no need to connect the modem to the Internet!):

There is no need to install anything for the RX108-R4.

Let's open the survey program:

In our example, the connected modem is assigned a COM15 port.

Let's fill in the parameters for communicating with a remote modem

Enter the SIM card number of the receiver modem

Type of interface through which we will make the request (GSM)

And press the button Connect

We see the connection process

The process of obtaining information can be observed at the bottom of the window

After 100% filling we will see the information read from the counter

After we receive all the necessary information and make the necessary settings, we must not forget Break established connection so as not to waste cash.

Additional Information.

Hi all!
With this publication we begin a series of articles about devices and technologies involved in the process of energy metering and energy saving. In such articles, we will rely only on our own experience and the experience conveyed to us by users of the Eldis electronic dispatcher.

Let's start slowly.

Today we have a general topic on our menu about CSD technology and modems that use this data transmission technology. We decided not to look for differences in two identical pictures, but to analyze CSD modems as such, without getting personal.

Surprisingly, the CSD modem uses information transfer technology called CSD when communicating with its fellow modems.

CSD (Circuit Switched Data) is a technology for transmitting digital data in GSM networks. The same network that each of us uses several times a day, or even spends the bulk of the weekday in it. I say hello to the technical support department =)

The CSD coverage area corresponds to the GSM coverage area, which is due to the use of the voice channel to transmit information. Today this is the main advantage and disadvantage of this technology. But first things first.

At the inception of CSD, the benefits were not limited to this, due to the lack of alternatives. The information transmission speed via CSD is 9.6 Kbps, while the throughput of modern 4G is 1 Gbps (kilobits - 10 to the 3rd power, gigabit - 10 to the 9th power). The technology involves two devices communicating with each other at the same time, similar to talking on a mobile phone or how a fax works.

CSD works in GSM networks, which means that for such a service, if we suddenly need it, we need to contact operators mobile communications. Yes, yes, these are the same guys who sell SIM cards for phones, and then offer new tariffs every month. Let's find out what they offer us today.

CSD traffic for mobile operators was valuable until every person had a mobile phone, and the price of communication fell to the minimum level, due to high competition between operators.

Why did the growth of mobile phone users begin to kill interest in CSD?

The fact is that when transmitting data from one device to another, CSD occupies a voice communication channel, which can be used for its intended purpose and at a higher price.

Also, as a standard for transmitting information, operators have an alternative with a higher throughput and does not load voice channels: GPRS, 2G, 3G, 4G.

In this regard, mobile operators are constantly increasing tariffs for CSD and, to the extent possible, eliminating it.

Today, the CSD service in most cases exceeds the price of even faster and more modern GPRS and is present only in specialized tariffs, implying CSD packages for several thousand minutes that operate within one region and one operator cellular communications.

Thus, cellular operators act as a catalyst in the process of destroying CSD technology.


Letter to Eldis JSC from MegaFon OJSC

The abandonment of CSD will not pass without a trace, and no, the retirement of this technology will not be accompanied by a magnificent holiday with tea and cookies, on the contrary, for the most part it will be painful. This technology successfully implemented and used to transmit readings from all kinds of electronic devices installed in hard-to-reach places.

Let's move on to our favorite topic.

After the release of Federal Law 261, which obligated the installation of metering devices in every apartment building, the task of quickly collecting readings from all installed computers became acute.

Without constant monitoring of energy metering nodes, there can be no talk of any energy efficiency, and assigning a person to each computer for monitoring is a very expensive pleasure.

Then CSD modems came to the rescue, attracting with their low cost (about 4 thousand rubles) and prevalence. Most standard software, included in the set of modern computers, supports work on CSD, for example: VKT-7 Easy2, Prolog, ArchiVist, Vzlyot SP, TesmaStat, StatReport and others.

With the advent universal programs for remote collection of readings from metering devices using various data collection and transmission devices (modems), CSD modems have another undeniable advantage - the ability to simultaneously work in several energy metering systems at once.

Thus, when working in one or another system for collecting readings from metering devices such as Eldis, owners of CSD modems do not take any risks and can at any time transfer their metering nodes to another similar system, unlike GPRS modems.

It’s sad, but not only CSD technology, but also modems that use it are at risk of disappearing from the shelves.

Recently, most manufacturers of radio components have begun to produce budget versions of SIM modules that do not have the function of operating in CSD mode. A striking example is the update of the SimCOM Sim900 line to Sim800. Now only one module from the entire 800 line has CSD mode. There is a suspicion that the next series of modules will be completely without CSD.

In total, the disadvantages of CSD modems include:

  • slow information transfer speed;
  • the polling speed of computers directly depends on the number of polling modems installed on the server, due to the impossibility of parallel communication between one CSD modem and several;
  • high price of traffic. About 1.25 rubles per minute, for the same money you can transfer 1 MB of information via GPRS (for text information that's really a lot. For comparison: the entire work of Tolstoy L.N. “War and Peace” occupies less than 4 MB.);
  • mandatory configuration of the modem to work with the computer is done using a computer via the RS-232 interface, which is not available on modern PCs and laptops;
  • the presence of only one data transfer interface, either RS-232 or RS-485;
  • lack of ability to remotely configure and update software;
  • threat of discontinuation;
  • the threat of eradication of CSD support by cellular operators;
  • The modem is disconnected from the dispatch system by default; it is connected only for the duration of data transmission and cannot always be online.

Despite all the shortcomings and antiquity of CSD technology, there are not enough fingers of both hands to count the manufacturers of CSD modems. While the technology has not outlived its usefulness and is not completely supplanted by mobile operators, there is good demand for it. The device is not difficult to manufacture and has a wide range of applications.

Basically, competing modems are not very different from each other. Most often, the main distinguishing feature is the case and the logo on it, less often the sim module. If we talk about the market leaders in terms of prevalence, we can highlight: iRZ, Teleofis and Siemens.

Let's summarize.

Modems using CSD technology, despite their wide popularity, are on the verge of extinction due to the threat of components for them being discontinued. Also, over time, the likelihood of mobile operators refusing to sell CSD services increases, and prices for CSD traffic are constantly increasing.

The cost of CSD modems is rapidly approaching the cost of modern modems that support GPRS. Both the rise in price of the former and the fall in price of the latter have an effect.

When choosing a data transmission device for installation at a dispatch site, we recommend paying attention to a CSD modem only if there is no alternative connection at the site, otherwise it is better to pay extra and purchase a modern device that works via GPRS or take a universal option - GPRS/CSD.

Note!
Not all modems whose specifications indicate operation via GPRS can independently communicate via GPRS, limiting themselves to the good old CSD.

Often this is a clever marketing ploy by manufacturers to mislead consumers and sell a CSD modem at the price of GPRS.

The trick is that the modem, without the help of additional equipment, be it a computer or a computer that will send specialized AT commands to it, is not able to initialize a GPRS connection. Heat calculators capable of sending such commands to the modem and making it work via GPRS are, for example, SPT943 and TMK-N120.

Let's return to the problem with GPRS coverage area.

Cases of the absence of a GPRS signal in the CSD coverage area are not a myth, and have happened more than once in our practice: in the Tver region (Ostashkov), in some cities of the Pskov region and even in the Krasnogorsk district of the Moscow region.

Based on statistics obtained during a survey of clients of the Eldis electronic dispatcher, modems operating only using CSD technology are today installed in approximately 75% of objects in relation to the total number of facilities equipped with transmitting devices. Complete refusal mobile operators from providing data transmission services via CSD will entail huge costs for the re-equipment of dispatch facilities.

Every month the number of CSD modems installed in Eldis increases significantly, and with it the monthly traffic to CSD communication also grows. The graph below shows statistics on the use of CSD traffic by all modems operating using this technology in the electronic dispatcher for the current year.


Dynamics of CSD traffic usage by Eldis users

With this article, we are not calling for urgent removal of old modems and buying new data transfer devices, but we are warning about possible difficulties in the near future.

We welcome requests for a review of devices from the list of supported equipment. We promise an objective assessment and adequate criticism of any device. If we don’t have enough materials to review the device you propose, sorry, we’ll postpone it until later.

An important role and incentive for writing articles is the presence of comments.

Thank you for your attention! That's all for today.

CSD (Circuit Switched Data) is a data transmission technology developed for GSM mobile phones.
GPRS (General Packet Radio Service) is an add-on to GSM mobile communication technology that provides packet data transmission.
GPRS allows the user of a cellular network to exchange data with other devices on the GSM network and with external networks, including the Internet. GPRS involves charging based on the volume of information transmitted/received, and not on the time spent online with CSD.
In CSD mode, a connection with a remote device is established by its telephone number, because This technology uses data transmission over voice channels.
In GPRS mode, the connection to a remote device is carried out using its IP address. For GPRS, communication channels are allocated on a residual basis after voice channels, i.e. Voice channels from cellular operators have higher priority than GPRS channels.

IMPORTANT : not all modems can be configured in such a way that after power is turned on, the modem is ready to accept a connection in GPRS mode (to connect to a modem, specify the modem’s IP address and the TCP port “listened” by the modem).

How to set up a CSD connection on iRZ modems?

Abbreviation CSD stands for Circuit Switched Data- data transmission by channel switching in the GSM network. A CSD connection is very similar to a regular voice call, which is why it is often called voice-over-data.
Below you can read exactly how to organize communication using this technology.

To work using CSD technology, all devices must be pre-configured.

You can configure modems manufactured by iRZ using the iRZ TestModem program. Other modems can be configured through the terminal program. The article will consist of two parts describing both methods.

To organize communication, we need two modems: a master, from which the telephone number will be dialed, and a slave, which will receive an incoming connection.

First of all, check that there is a positive balance on the account of the SIM cards installed in the modems.

Make sure that your mobile operator has activated CSD data service on both SIM cards.
Now connect the devices you want to configure to your computer via the RS232 interface. If there is no such interface, use an interface converter USB-RS232. For modems with RS485 or RS422 interface, a converter is required USB-RS485/422.
Apply power to the modems, wait for the modems to register in cellular network(LED blinking will become short-term and infrequent).

Preparing iRZ modems for operation using CSD technology using the iRZ TestModem program.

Download and install the iRZ TestModem program for your version of the operating system.
Next, run TestModem and select your device from the list.

If you know the number COM port and then you can indicate it in the section " Port Settings", otherwise the program will try to detect the modem on its own.

Click " Begin". Once the status indicator turns green, go to the " tab Settings".

In chapter " Mode" select the interface speed. It must match the speed of the equipment connected to the modem. As a rule, the standard speed is used 9600 bps.
The modem that will dial phone number, set to " Leading". Set the modem that will accept incoming connections to " Slave". Click the " button Begin". After setup, the modem will be turned off and for further operation it will need to be rebooted by briefly turning off the power.

Preparing iRZ modems for operation using CSD technology using a terminal program.

Here is a list of AT commands for configuring modems:

Setting up a master modem(the call will be initiated from his side):Setting up a slave modem(the modem will accept incoming connections):

at&f
at+ipr=9600

at&d0(ignore DTR)

ate0(disable echo)

at&w(preservation)

at^smso(shutdown)

at&f(pre-reset)
at+ipr=9600(baud rate via COM port)

at^scfg="GPRS/ATS0/withAttach",off

ats0=1(auto answer after one ring)

at&c0(determination of DCD mode)

at&d0(ignore DTR)

at+cbst=71,0,1(switch the modem to data receiving mode)

ate0(disable echo)

at&w(preservation)

at^smso(shutdown)

Run Terminal 1.9b, install optionsport on the modem, select COM port, to which it is connected and press the button " Connect"

In the command input field, check the box " +CR" and enter the first command. Send it to the modem by pressing the " button ->Send".
Make sure that the modem sent confirmation of the command - response " OK"

Sequentially enter the entire set of AT commands given in the table above. After giving the last command " AT^SMSO"The setup will be completed. To continue working, you must briefly disconnect the power from the modem.

(the same as in computers), either built into the phone or attached to it. Due to limitations in audio signal quality, such systems had a maximum data transfer rate of 2.4 kbit/s. At the same time, GSM's use of speech-oriented audio compression effectively means that data transfer rates using such a modem connected to a telephone will be even lower than traditional analogue systems. With the advent of digital data transmission in GSM, CSD provided practical direct access to the digital signal, allowing higher speeds to be achieved.

A CSD call works very similar to a regular voice call on GSM networks. A single time interval is allocated between the phone and the base station. A dedicated "sub-time slot" (16 kbps) is established between the base station and the transcoder, and finally another time slot (64 kbps) is allocated for data transmission between the transcoder and the switching center: Mobile Switching Center (MSC).

In MSC it is possible to convert the signal into analog form and encode it using PCM. It is also possible to use digital signal according to the ISDN standard and transferring it to the remote access server.

Data transmission on GSM networks has been improved since the introduction of CSD. As of 2006, many GSM operators provide CSD service. Since the maximum data rate for a single time slot is 9.6 kbit/s, many operators allocate two or more time slots for CSD calls.

Technology development

HSCSD ) - a system based on the same principles as CSD, but designed to provide faster communications. Speed ​​increased to 57.6 Kbps

ECSD - data transmission using EDGE technology over the CSD channel.

On the other hand, GPRS General Packet Radio Service) provides packet data transfer directly from a mobile phone.
And, in fact, EDGE (eng. Enhanced Data Rates for GSM Evolution] ) and UMTS (English) Universal Mobile Telecommunications System ) provide access at much higher data rates, but are still compatible with the GSM standard.

see also

3G (IMT-2000)
Intermediate after 3G
(3.5G, 3.75G, 3.9G)

(IMT-Advanced)
see also

Wikimedia Foundation. 2010.

See what "Circuit Switched Data" is in other dictionaries:

    Circuit Switched Data- (CSD) is the original form of data transmission developed for the time division multiple access (TDMA) based mobile phone systems like Global System for Mobile Communications (GSM). CSD uses a single radio time slot to deliver 9.6 kbit/s data... ... Wikipedia

    Circuit Switched Data- (CSD) es la forma original de transmisión de datos desarrollada para los sistemas de telefonía móvil basados ​​en el acceso múltiple por división de tiempo (TDMA) como el GSM. CSD usa un intervalo de tiempo (time slot) de radio individual para… … Wikipedia Español

    Circuit Switched Data- ist ein Übertragungsverfahren beim Mobilfunk, bei dem eine Datenverbindung vom Mobilfunktelefon zu einer (beliebigen) Gegenstelle hergestellt wird. Diese Verbindung ist mit einem einfachen Telefongespräch vergleichbar. Im Unterschied dazu werden… …Deutsch Wikipedia

    Circuit Switched Data- Pour les articles homonymes, voir CSD. Le Circuit Switched Data (CSD) est la forme originale de transfert de données développée pour les systèmes de téléphone mobiles basés en technologie TDMA comme le GSM. Il a un fonctionnement similaire à… … Wikipédia en Français

    circuit switched data- A method for keeping the circuit open between users for the duration of the connection … IT glossary of terms, acronyms and abbreviations

    High-Speed ​​Circuit-Switched Data- (HSCSD), is an enhancement to Circuit Switched Data, the original data transmission mechanism of the GSM mobile phone system, four times faster than GSM, with data rates up to 38.4 kbit/s.As with CSD, channel allocation is done in circuit... ... Wikipedia

    High-Speed ​​Circuit-Switched Data- (HSCSD), es una mejora al mecanismo de transmisión de datos de GSM o circuit switched data (CSD). Fue aprobado por la ETSI en 1997 y fue desplegado por varios operadores de GSM en el mundo. HSCSD introduce dos modificaciones tecnológicas que… … Wikipedia Español

    High Speed ​​Circuit Switched Data- (HSCSD) est une technologie dont le but est de fournir un débit plus élevé pour les applications nécessitant des transferts de données. Le GSM utilise le TDMA, c est à dire que le temps est divisé en slots (période donnée). En GSM, un mobile... ... Wikipédia en Français




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