Area Remote Terminal Unit
The Area Remote Terminal Unit (A-RTU) may manage up to 8 remote sites in a SCADA / Telemetry
Monitor and Control System and replicates a portion of the control algorithm that resides in the System Control
Computer (SCC). The area control algorithm and the assignment of the related remote sites allow the A-RTU
to function independently of the SCC in a stand-alone mode or to continue functioning in the event of SCC failure.
As a stand-alone unit, the A-RTU may provide an alternative to PC based Monitor and Control Systems without sacrificing
future expandability to a SCC or basic functionality within the SCADA / Telemetry Monitor and Control System.
The A-RTU incorporates the following:
- A wall mounted NEMA 4 cabinet with an 8 x 40 line LCD screen and 20 pushbutton keypad used as an operator
interface for data monitoring and control loop programming.
- Power supply, battery backup, radio, radio modem, and synthesized voice telephone alarm dialer (optional).
- The programmable, non-volatile EEPROM memory is capable of being modified, expanded, or reconfigured via the wide area
radio network (WAN), a telephone modem, or a laptop computer serial connection.
- The A-RTU has two RS232 serial ports expandable to 4 serial ports.
- The A-RTU uses a card cage design for expandability.
- 8 Analog Inputs expandable to 16; Characteristics: 8 or 10 bit, 4-20ma / 0-5vdc / 1-5vdc.
- 8 Digital Inputs expandable to 64; Characteristics: ON / OFF, 12vdc, 24vdc, 120vac, dry contacts, isolated.
- 4 Counter Inputs expandable to 56; Characteristics: 16 bit or 32 bit, ON / OFF, isolated.
- 1 Analog Outputs expandable to 16; Characteristics: 4-20nam 0-5vdc.
- 8 Digital Outputs expandable to 64; Characteristics: ON / OFF, 120vac @ 5 amp resistive dry contacts.
- Operate on nominal input power of 105-135 volts 60Hz with a 12-volt battery backup.
- Incorporate over-voltage protection on all input/output connections, supply power connections, and antenna connections.
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All A-RTUs have the following characteristics:
- Microprocessor based, interrupt driven, and multi-tasking operating system. 16 bit 8 MHz processor. 32kB RAM. 32kB ROM. Capable of utilizing Intel data formats.
- Can be networked by radio, phone, cellular, RS 232 cable, RS422 / IEEE 485, fiber optic or internet.
- Peer-to-peer communication and multi-protocol recognition.
- Capable of route store-and-forward repeating of remote location data and information.
- Has a unique two part identification address. The address is digital utilizing the hexadecimal numbering system
and occupies a minimum of two bytes of memory.
- Capable of serving as a local area or process controller and / or executing System Control Computer (SCC) commands.
- Capable of monitoring and controlling site functions and status.
- Reports site alarms as they occur in a 'report by exception' format.
- Parameters set locally or remotely.
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All A-RTUs have the following programmable functions and features:
- Differential pressure calculations.
- Square root and absolute value functions.
- Flow rate and totalization calculations.
- 32 bit signed math capability.
- Programming functions of AND, NAND, OR, NOR, XOR, XNOR, INVERT.
- Pump Alternator, Runtimes and Cycle Counters.
- Level Controller.
- High Speed Counters.
- High / Low Alarm Indicators.
- Data Logging (93 hours).
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