• The SC1801 protocol is a more hardware-oriented communication protocol perfectly suited for all generally used telecontrol functions in control and monitoring directions. The functionalities of original SC1801 operated RTUs are determined by the range of various plug-in modules, for instance for digital input, counter input and analogous output. This modular structure comes in useful when it comes to addressing information.

    The small address buffer needs to be mentioned. For instance only 384 single indications can be processed per RTU, if ALL 16 available plug-in slots have been used/configured for digital input modules. There is no space left for other kinds of messages and the same applies to measured values (129) and counter values (128). And this is before the control direction is even considered.

    SC1801 operates in half-duplex communication mode based on the master/slave principle. An RTU only responds to an explicit request by the master.

7 Application Layer SC1801 Application Layer
6 Presentation Layer n/a
5 Session Layer n/a
4 Transport Layer n/a
3 Network Layer n/a
2 Link Layer n/a
1 Physical Layer RS232 / V.24 (UART-Conform)
Supported Information Types
Control Direction
  • Single Command
  • Setpoint [12 bit]
Monitoring Direction
  • Single indication [1 Bit]
  • Single indication [1 Bit] with time tag
  • Measured value [12 bit]
  • Counter value [16 bit]
Protocol Features
  • Physical Layer

    RS232 / V.24 (UART-Conform), Half-Duplex

  • Application Layer

    Transmission of pulse commands with definable pulse length
    Transmission of setpoints, bit patterns and counter management commands
    Spontaneous transmission of indications with or without time tag, measurands and counter values
    Absolute time tag representation, accuracy 0.1 ms
    General Interrogation
    Time synchronization

  • Address Space

    rtu's per line: 255
    Indications for each rtu: up to 384
    Measurands for each rtu: up to 192
    Counters for each rtu: up to 128
    Commands for each rtu: up to 256
    Setpoints for each rtu: up to 128

Available Protocol Stacks

SC1801, Slave

Applicable Products
  • ipConv

    Universal protocol converter for highest degree of flexibility

    FSC HECHI, China

    Products: ipConv
    Protocol Stacks: SC1801, Slave IEC 60870-5-104, Slave IEC 60870-5-101, Slave Simadyn-D, Master