Data transfer via csd. CSD. Description and information of CSD. Packages for machine communication

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, when communicating with its fellow modems, uses an information transfer technology called CSD.

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 mobile operators. 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 higher bandwidth and which 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 the faster and more modern GPRS and is present only in specialized tariffs that imply CSD packages for several thousand minutes that operate within one region and one cellular operator.

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 has been successfully implemented and is 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 promptly 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 of the standard software included with modern computers supports CSD work, for example: VKT-7 Easy2, Prolog, ArchiVist, Vzlyot SP, TesmaStat, StatReport and others.

With the advent of universal programs for remote collection of readings from metering devices using various data collection and transmission devices (modems), CSD modems have revealed 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 this is really a lot. For comparison: the entire work of L.N. Tolstoy “War and Peace” takes up 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.

Pay attention!
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. A complete refusal by cellular operators to provide 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.

Let's start slowly.

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

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 higher bandwidth and which 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.

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

Letter to Eldis JSC from MegaFon OJSC

Let's move on to our favorite topic.

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.

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

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 this is really a lot. For comparison: the entire work of L.N. Tolstoy “War and Peace” takes up 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.

Let's summarize.

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.

Pay attention!
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.

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

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.

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

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

How to activate the service and gain access?

If you do not have an agreement for communication services with MegaFon PJSC, you need to contact the Corporate Customer Service Center, conclude an agreement and write an application to connect to the M2M-Monitoring service. If you are already a corporate client, you can independently activate the service through your “Personal Account” or submit a written application in the form established by the Operator.

How to log in via API?

URL: https://m2m.megafon.ru:3333
Request format: https://m2m.megafon.ru:3333/openapi/v1/tokens-stub/get?login=M2M_xxxxxxxxxx&password=xxxxxxxx

How to enter the service interface?

Follow the link “Personal Services Account” at the top of the screen. On the authorization page, you must enter the login and password received via SMS to the service user’s subscriber number, as well as the symbols located in the picture. The user has four attempts to enter an incorrect password to access the service interface. After the fifth entry of an incorrect password, access to this login is blocked. The user has the opportunity to obtain a new password through the service interface, or by contacting the corporate customer service center.

How is the Subscription fee calculated?

When connecting to the M2M Monitoring service, all corporate clients are provided with a test period of 7 calendar days, during which no subscription fee is charged.

In the first month, the subscription fee is debited from the Personal Account of the Corporate client on the first day of paid use of the service based on the number of SIM cards with the connected service in proportion to the number of days remaining until the end of the month. Subsequently, the subscription fee is debited in full on the first day of each month.

Which companies is this service intended for?

"M2M Monitoring" will be useful to all companies using SIM cards in devices and equipment. The service may be useful for companies working in the field of vehicle monitoring, banks and trading enterprises, auto manufacturers, companies in the energy and housing and communal services sector, fuel and energy companies, as well as companies specializing in security services, security, logistics companies, manufacturers of consumer electronics and system integrators.

Is it possible to connect M2M Monitoring yourself?

If your company is a corporate client of MegaFon PJSC, then you can independently connect M2M Monitoring through your personal account on the Corporate Portal. To do this, you need to connect to SIM card numbers with any corporate tariff plan:

“M2M Monitoring” to load the required SIM card onto the M2M Monitoring Service platform and the ability to manage it through the Service Interface;
M2M portal User - a setting that allows you to identify the user of the Service and provide access to manage SIM cards through the Service Interface;

M2M Portal Administrator - a setting that allows you to identify the administrator of the Service and provide access to manage SIM cards through the Service Interface.

The login and password for accessing the M2M-Monitoring service interface will be sent via SMS to the number of the employee who is connected to the “M2M-portal User” or “M2M-portal Administrator”.

What notification capabilities does the service have?

You can set up alerts for various events, for example, for changing the device in which the SIM card is installed, for reaching data transfer limits, SMS, voice communication services, etc. You can also regulate the sending of notifications and configure sending parameters: email address, phone numbers to receive SMS notifications.

What messages can I send using the service?

You can send messages to selected numbers with the M2M Monitoring service activated to determine the activity of the SIM card on the network. You can also send messages to the numbers of Russian mobile operators entered in the “Contacts” section in the service interface.

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 the cellular network (the 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 COM port number, you can indicate it in the " 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 the section " 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.
Set the modem that will dial the phone number 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(save)

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(save)

at^smso(shutdown)

Run Terminal 1.9b, install parametersport 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.

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

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.

Before the advent of CSD, data transfer in mobile phones was accomplished through the use of a modem, 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. With the advent of digital data transmission in GSM, CSD provided practical direct access to the digital signal, allowing higher speeds to be achieved. At the same time, GSM's use of speech-oriented audio compression effectively means that data transfer rates using a regular modem connected to a telephone will be even lower than traditional analogue systems.

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).

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