The Elpro 105 range of telemetry modules provide remote monitoring and control by radio or twisted-pair wire, over short or long distances. Transducer signals connected at one module (input signals) are transmitted to another module where the signals are re-created as output signals or passed via RS232/485 to a host device such as a PLC or scada system.
Easy to use
The modules have been designed to be easy to use and simple to install. They include power supply, microprocessor controller, input/output (I/O) circuits, radio transceiver and/or serial transceiver (RS485/232). The 105 modules are completely integrated and ready for use. They are housed in a strong extruded aluminium case, with plug-in terminal strips for ease of wiring connection and maintenance.
105U radio telemetry modules
The radio telemetry modules are a low-cost alternative to cable installations. The 105U provides a wireless radio link for digital (switch contact), pulse and analog signals. As well as radio communications, the 105U has a port for RS485 multidrop twisted-pair cable, enabling communications to 105S serial telemetry modules.
105S serial telemetry modules
The 105S range of modules provide communications via RS485 multidrop. RS485 is a method of transmitting between many devices using a common twisted-pair wire. The maximum length of the wire is typically 2000 m. This method of communications is particularly suitable for enclosed factory environments where distances between modules are not very far, however radio paths may be obstructed. 105S modules may be used as a separate multidrop I/O system or as I/O expansion for 105U modules.
In factories or building environments, groups of 105S modules, connected by RS485 multidrop, may also transmit information by radio to another remote multidrop group in another building. For example, several buildings on a large site may be connected by radio links, with signals inside the buildings being conveyed by multidrop twisted-pair.
Simple but reliable
The Elpro 105 modules use a very reliable transmission protocol designed for secure communications, even with external interference. Because 105 modules have transceivers, modules are able to communicate with each other to control the flow of information.
Transmissions occur when an input signal changes. That is, when a digital (switch contact) input turns off or on, or when the value of an analog input changes by a pre-configured amount. The 105 provides realtime communications, which polling systems cannot achieve.
There are also regular update transmissions to check the value of the input signals and to check the integrity of the communication path. The status of the comunications path is available as an alarm output.
The input signals are transmitted in a 'data frame' which includes the address of the transmitting module, the address of the destination module and a CRC error check. The error check is used to ensure that there is no corruption of the data frame during transmission.
Each module will wait until the radio channel is 'free' before transmitting a message. When the destination module receives the message, it will check the validity of the message and transmit a return acknowledgment - a 'handshake'. If the original module does not receive this acknowledgment, then it will resend the message another four times. Using this simple but secure communications protocol, the 105 provides reliable operation even in noisy environments.
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