Siemens Telemetry/RTU Project

[andreik 0]

Good day, I've been a PLC Programmer for almost 7 Years now but neved did I encounter a Telemetry System before. What's more, I've never even worked with a Siemens PLC before. I am about to estimate a "16 Water Borehole" project that are all within a 20km radius. The Main Station w/c is within the area is where the Main Controller & SCADA is going to be. The system control is actually simple; each of the 16 Water Boreholes are only designated with 32 Digital I/O's each. The pumps are basically ON/OFF with trip signal and the Water tank level monitoring is just determined by the usual Float Switch (low, mid, high levels). For an overview, please see the attached document. The problem is, I don't know where to start. I've tried browsing the Siemens website but I find it vague, tortuous and not helpful at all. If someone could give me an overview how Telemetry system works, the hardwares and softwares required etc. I will very much appreciate it. Thank you so much, Andrei K. Borehole_Tele_Proj.ppt

[Rod_Hackney 2]

You need to identify what type of Siemens PLC you are going to use. Then you next task is to determine the communications you are going to use. Wireless, phone lines, sat ect... within the wireless realm there is a license free spread spectrum range and licensed bands. Many questions come up with communications - are the sites in line of site of each other? Does the owner already have a license for freq he uses for scada? After you answer the communications question then you can select hardware that will support that communications with the Siemens PLC you want to use, communication protocol (DNP3, Modbus etc... ) and Scada Software.

[andreik 0]

Communications... I'm not really sure because the one who briefed me actually knows nothing. He wants to assume that his little information should be enough. Anyway, perhaps we can use GPRS or Internet or both. Let's assume that we have a line of sight for all stations to the main station. I just want to have a general idea for now. Could you share with me a simple, ideal configuration? Let's say 2 stations with 5 I/O's each to be connected to a Main Station w/ Scada. Frequency uses for Scada? Nothing at all. Everything will start from scratch. I'm thinking about either S7-1200 or S7-300 at the Main station. Maybe I'll just connect the Scada to that PLC. thank you so much. Andrei K.

[Groo 7]

The native communication with Siemens is PROFIBUS or PROFINET, I've seen countless installations over here in Canada where Modbus is used, it adds complications, so if you can find equipment that converts the signals to one of the native protocols it would be easier. Most common link if you have line of sight is radio, so you would need to source radio transmitter receivers and as mentioned above look at the frequencies available and costs for these. If you can source equipment with Siemens native comms then that would be preferable, only go non native if you have no other choice, but it will add to the development. Of course radio is not the only choice, I have heard satelite amongst others. The PLC part itself is simple, its just standard control, the telemetry part is linking those PLC's to your central station, so its just communication. Converting signals between the SCADA to the PLC and the radio signal in between. I've worked on some older installations which used forms of serial but I would be sure there should be Ethernet versions nowadays, do some research and call in some specialist companies to give you ideas and let you know what is available and the cost of each choice.

[Groo 7]

As a foot note, for small applications I would get S7-1200's, the 300 is being replaced by the S7-1500's anyway. Radio frequencies in Canada, there are some public frequencies available but these are insecure, you have to purchase the right to use private frequencies for the radio transmissions, these can include expensive annual fees. A central radio mast installation would be needed too.

[Rod_Hackney 2]

check out this siemens link: http://www.automation.siemens.com/mcms/industrial-communication/en/industrial-wireless-communication/network_components/Pages/network-components-iwlan.aspx

[andreik 0]

I'm opted to use Radio Telemetry and I think what suitable to my application is the DNP3. I've searched the Siemens website and found various wireless solutions. Most of them are linked to the Internet via GSM but it is not good use GSM here in Botswana mainly because we have poor Mobile services and connectivity in here.