Concentrator (Remote Terminal Unit – RTU)
The Concentrator or RTU is the equipment to which the devices to be controlled are connected.
The unit has a fan less PC Embedded MINI ITX and can be housed in a 19" rack. The task of the concentrator is to acquire, directly or indirectly, the information to be monitored at the control centre by means of physical and logical interfaces. The activities performed by this unit are configured and monitored centrally by means of the software described previously.
Some examples of RTU functions:
- Normalisation of data streams. If the data streams acquired are not homogeneous, the RTU normalises them, implementing suitable communication protocols.
- Rule configurations. It is possible to configure rules to filter and/or aggregate alarms, or assign a degree of severity on multiple levels.
- Local Automation. The RTU can perform local automation using a simple script mechanism. Such automation can be used to create virtual alarms or correlations between analogue inputs / thresholds and outputs.
- Data logging. All data collected (including analogue measurements) are logged in a non volatile flash memory of the RTU and tagged with date / time. The data logged information then await downloading in the control centre. In all cases, the high severity alarms generate spontaneous and priority reporting procedures.
Communication between the RTU and control center
The RTU is capable of communicating with the control centre using any available channel of communication, when necessary it can be fitted with an external interface. The RTU must be able to connect to the control centre via GPRS using a GSM / GSM-R modem, or to local data network by means of a FastEthernet interface (called a WAN). In addition, the presence of the RS232 interfaces makes it possible to use external modems.
Secure transmission and data correctness
AUSIF implements an ad hoc transmission protocol. Unlike other protocols it is able to guarantee the safe delivery of the information. This is a distinguishing feature of AUSIF, which guarantees the correctness of the information displayed. The user is informed about any failure to update the data so as to provide a true and undisputable picture of the data displayed. The AUSIF transmission protocol guarantees correct delivery of the information!
The RTU is equipped with internal backup batteries so that during a power failure the system can send all information to the central unit in due time (30 minutes minimum battery life).
RTU operating status control
The operating status of the RTU is also remotely controlled from the control centre from which it is possible to manage and change the RTU configuration. The RTU has a watchdog mechanism that safeguards its operation.
Data acquisition from peripheral devices
The acquisition of data from peripheral devices can be carried out in several ways:
- By using the SNMP protocol, acting as a "manager". The RTU will query the OID of the devices connected on the local network (via a Fast Ethernet, known as LAN).
- By using its three RS232/RS485/RS422 interfaces (configurable), using specific protocols to be implemented under certain specifications.
- By using special I/O interface cards, connected to the RTU RS485 interface using a protocol defined by the manufacturer.