Evgenii Legotckoi
Evgenii LegotckoiApril 7, 2016, 12:07 p.m.

PTZ-camera control. Pelco-D protocol

Pelco-D - is a PTZ-camera control protocol developed by the same name by Pelco. As a rule, used over RS482/485 interface for communicating with cameras equipped with servo drives.

Pelco-D protocol has in the arsenal of a set of standard commands, as well as advanced instruction set. This article will look at how to work with a standard set of commands. Protocol Pelco-D Let us examine the example of the abstract and the abstract command source SDK, which receives the message for onward transmission to its RS485 interface. This reservation was made deliberately, because it is such a challenge recently stood in front of me.

Therefore there is a protocol by which data is transmitted, and further understand the data transmitted to the SDK, which sends a message already in the RS485 transmission path. Below is a picture in which there is a yellow square. It is in this function and will form the necessary us the message you want to convey in the SDK.

Message Structure

Post Pelco-D protocol consists of 7 bytes. Let us analyze the value of each byte:

  1. Byte synchronization - always has #FF value in hexadecimal;
  2. Address - address byte PTZ-camera or any other device on the RS485 / 482 line;
  3. Command 1 - the first byte standard commands Pelco-D;
  4. Command 2 - the second byte standard commands Pelco-D;
  5. Data 1 - byte rotation speed camera left / right, is from #00 to #3F;
  6. Data 2 - speed bytes tilt the camera up / down, is from #00 to #3F;
  7. Checksum - is an 8-bit bytes by the sum of the 2nd to 6th.

Standard set of commands

To send the message must be necessary to form two teams messages. If the data will not be passed on, then it will be necessary to set the zero value bit responsible for this or that functionality.

Consider the structure of commands.

Sense bit charge is meaning of bits 3 and 4. When the bit is lifted, the set bits 3 and 4 have the camera and the auto scan switch, respectively, otherwise raised by bits 3 and 4 have the shutdown. Bits 5 and 6 are reserved and should be set to 0. Other settings are responsible for the diaphragm (Iris), Focus (Focus), Zoom (Zoom), Tilt (Tilt), Rotate (PAN). To enable these parameters should be set to activate the corresponding bits in the unit.

Examples of commands

Rotation to left: FF 01 00 04 00 00 05
Rotation to right: FF 01 00 02 00 00 03
Tilt up: FF 01 00 08 00 00 09
Tilt down: FF 01 00 10 00 00 11
Zoom +: FF 01 00 20 00 00 21
Zoom -: FF 01 00 40 00 00 41

Sample code

In this abstract code was created in a vacuum, such a situation that the function of these values fall:

  • address;
  • PanSpeed - rotation speed with the direction, from - 100 to +100;
  • TiltSpeed - Tilt speed with the direction, from -100 to +100;
  • ZoomSpeed - Zoom speed with direction, from -100 to +100. Why so submitted data for Zuma - is a question for me, given that Pelco is no speed setting, but that is what it is.

But SDK has already formed a team takes a pointer to an array of data, and an indication of the length of the array. The result is the following code.

void ptzCmd(int addressPTZ, int panSpeed, int tiltSpeed, int zoomSpeed)
    unsigned char *dataPelco;
    unsigned char address, command1, command2, data1, data2, checkSum;
    address = command1 = command2 = data1 = data2 = checkSum = 0x00;

    dataPelco = (unsigned char*) malloc(7);

    address = (unsigned char)addressPTZ;
    if(panSpeed < 0) {
        command2 |= 0x04;
        panSpeed *= (-1);
    } else if(panSpeed > 0) {
        command2 |= 0x02;
    data1 = (unsigned char)panSpeed*63/100;

    if(tiltSpeed < 0) {
        command2 |= 0x10;
        tiltSpeed *= (-1);
    } else if(tiltSpeed > 0) {
        command2 |= 0x08;
    data2 = (unsigned char)tiltSpeed*63/100;

    if(zoomSpeed < 0) {
        command2 |= 0x40;
    } else if(zoomSpeed > 0) {
        command2 |= 0x20;
    checkSum = address + command1 + command2 + data1 + data2;
    checkSum %= 100;

    dataPelco[0] = 0xFF;
    dataPelco[1] = address;
    dataPelco[2] = command1;
    dataPelco[3] = command2;
    dataPelco[4] = data1;
    dataPelco[5] = data2;
    dataPelco[6] = checkSum;

    sdk_write_pelco_cmd(7, dataPelco); // 7 - это длина сообщения
We recommend hosting TIMEWEB
We recommend hosting TIMEWEB
Stable hosting, on which the social network EVILEG is located. For projects on Django we recommend VDS hosting.

Do you like it? Share on social networks!


Only authorized users can post comments.
Please, Log in or Sign up

C++ - Test 002. Constants

  • Result:41points,
  • Rating points-8

C++ - Test 001. The first program and data types

  • Result:80points,
  • Rating points4

C++ - Test 001. The first program and data types

  • Result:53points,
  • Rating points-4
Last comments
Evgenii Legotckoi
Evgenii LegotckoiDec. 3, 2023, 4:39 p.m.
Django - Lesson 059. Saving the selected language in user settings It is redirect from untranslated url to translated url. It is normal behavior for mutlilanguage web site based on the Django.
coder55Dec. 2, 2023, 1:34 a.m.
Django - Lesson 059. Saving the selected language in user settings It tries to do language translation in API views. That's why it sends or receives the same API request twice. Do you have any suggestions on this? Example: stripe webhook. "GET /warehouse/…
gr1047Nov. 12, 2023, 6:35 p.m.
Qt/C++ - Lesson 035. Downloading files via HTTP with QNetworkAccessManager Добрый день. Изучаю Qt на ваших уроках. Всё нормально работает на Linux. А под Win один раз запустилось, а сейчас вместо данных сайта получается ошибк "Unable to write". Куда копать, ума не…
DamirNov. 2, 2023, 10:41 a.m.
Qt/C++ - Lesson 056. Connecting the Boost library in Qt for MinGW and MSVC compilers С CMake всё на много проще: find_package(Boost)
Павел Дорофеев
Павел ДорофеевOct. 28, 2023, 9:48 p.m.
Как написать свой QTableView Итак начинаем писать свои виджеты на основе QAbstractItemView. А что так можно было?
Now discuss on the forum
BlinCTNov. 30, 2023, 5:18 p.m.
Сборка проекта Qt6 из под винды на удаленой машине Всем привет. Сталкнулся с такой странностью: надо собирать проект из под 10 винды на удаленой линуксовой машине, проект строится на QT6, но вот когда cmake генерит свой кеш то вылитает…
Evgenii Legotckoi
Evgenii LegotckoiNov. 19, 2023, 4:14 p.m.
CKEditor 5 и подсветка синтаксиса. Добрый день. Я устал разбираться с CKEditor и просто перешёл на использование самописного markdown редактора...
Виктор Калесников
Виктор КалесниковOct. 20, 2023, 11:29 a.m.
Контакты Android делал в далеком 2017г поэтому особенно ничего не подскажу. Это основные методы получения данных с андроида используя Qt. Там еще какоето колдунство с манифестом. Андроидом давно не занимаюс…
mihamuzOct. 18, 2023, 9:03 p.m.
Скачать Qt 6 Сработал следующий алгоритм. Инстолятор скачал используя это https://freevpnplanet.com/ru/ как расширение браузера. Потом установил это https://freevpnplanet.com/ru/ же на ПК и через инстолятор …

Follow us in social networks