What can we improve?





The power control module EKM 868 is a 4-channel module with 32-bit counter, which counts of four inputs and records their duration. The bidirectional data transmission takes place via a USB radio transceiver operating in the 868 MHz frequency band. It is used to visualize and projection of consumption costs in conjunction with IP Symcon. The count remains valid as long a power supply consists (9V = power adapter). A clear (reset) of the count by a power outage is detected by IP Symcon, a battery backup is therefore not required. The running PC you only need to provide a single value with a timestamp and to generate graphics. A special feature of the EKM 868 is that in addition the current power (consumption) is recorded.


To query counter data, first the virtual Comport driver on Windows must be installed and the USB radio transceiver must be connected.


Now add a new EKM 868 (manufacturer: IP Symcon/ ProJet):

EKM-868 Configuration
Value Description
DeviceID Default 128 is predetermined. When two EKM 868 are present in a system, in the device a jumpers can be set: the two lower pins (direction Header, upper PIN: NC). The new ID is then 129. ATTENTION: If red LEDs are installed (1 to 4), the ID is 129 by open Jumper! Devices with the ID 130/131, etc. are available on request.
CounterID The ID corresponds to the respective inputs (channels): 1,2,3,4
Modus: Read counter It is read out the count (Variable: Counter) and the time interval in 1/100 seconds between two impulses (Current).
Modus: Read on-time The duty cycle (closed contact) is returned in 1/10 seconds (at 32 bits this results in a period of more than 13 years!)
Modus: Read off-time The off-time (contact open) is returned in 1/10 seconds
Impulse At electricity meters the impulses are entered per kWh. The unit of the variable "Current" is then also kWh. At 0 is the unit 1/100 second - ideal for e.g. to determine the volumetric flow of gas or water meter.
Timer activated With a set tick values ​​are queried in the specified time interval. This is limited to a minimum of 60 sec.
Test Center A command for output values ​​will be sent to the EMK. When properly installed, the variables in the object tree are updated accordingly.

The inputs are not galvanically isolated - they must not exceed 5V. At plan view, the common ground of the four inputs is the right connection. At every entrance, an RC element was installed: 1K to as pull-up and 100nF mass. A switching e.g. with a reed contact to ground causes a count. The power supply must not exceed = 12V. Higher voltages or reversed polarity lead to destruction of the device. Then, an external protective circuit (Z-diode, resistor) is to provide.

Tips & Tricks

  • The internal timing (Current) has a resolution of 16-bit and 1/100 overclocking.
    This means it can be detected pulse sequences of a maximum length of 655 seconds (almost 11 minutes). In case of an overflow, an -0- is returned.
  • Internally, the following formula is used to convert the current power in watt:
    P = (3600 1000) / (Current / 100 Impulses) [Watt]
    Where "Current", is the time between two pulses in 1/100 seconds
  • To display the current energy consumption (energy-light), in practice intervals of 20 minutes revealed to be optimal.
  • Power supply: Please be sure to use the supplied = 9V power supply - no "bell transformer"
    Internally, a low drop 3.3 V voltage transformer is installed.
    The input voltage ranges from 5.0 V = to = 10.0 V. The inner contact of the DC socket is the positive pole.
  • If the counter e.g. is erased by a power failure, so this is not relevant because IP Symcon detects it automatically and takes it into account when generating the graphics

Problem: LED lights permanently
Solution: If necessary, swap the wires of the respective counter input (electronically)
or wait until the counter continues to rotate and releases the reed contact (mechanical).

Technical data

  • Dimensions (without antenna): 70 70 25 mm
  • Weight: 100g
  • Power supply: 9V bis 12V DC / 100 mA / Connector: DC socket for hollow plug 2,1mm
  • 4 S0 Inputs / 4 32-Bit counter (TTL – 5V)
  • maximum count frequency: 100 Hz
  • minimum pulse length: 20 msec (debounced internally for mechanical contacts)
  • Protection class: IP 20
  • Radio module: 868MHz (PC radio interface: USB-T 868 is not included)