LRC-M1 and LRC-L1 Remote Control
User Manual
9
9M02-7634-A001-EN
Version 3
3. General
With an OCU and a matching MCU, a machine such as a crane or vehicle can be remotely radio controlled,
avoiding the need for a wired connection between the human interface and the controlled device. A number of
different control elements are integrated into the OCU housing so that commands to the device are securely
encoded into a radio transmission. The MCU is then able to receive this transmission, securely decode these
commands, and provide suitable interfaces to drive the machine.
3.1
Radio Transmission
The transmission between the OCU and MCU is performed by means of radio communication. With regard to the
actual radio frequency that is used, there are several radio frequency bands available. A specific RF channel must
be selected within the respective frequency band. Depending on the frequency band, a certain number of RF
channels are available. For details regarding the available standard RF channels please refer to the
sections of this document. Other frequency bands may be designated and deployed.
The OCU and MCU must operate on the same RF channel in order to be able to communicate.
3.1.1 Continuous Transmission
Typically, transmission is continuous and the MCU uses this as part of the information required to maintain the
safety relays in an active state. If the MCU does not receive a valid telegram in this mode for a certain period of
time (defined as PNH-Time), it automatically turns off; i.e., safety relays and command relays open. Depending on
the application, the PNH-Time varies from 0.5 s to 2.0 s.
In order to ensure optimum communication between the OCU and the MCU in this mode, ideally operate the OCU
with line of sight to the MCU or its antenna at all times. Avoid total shielding by metallic obstructions.
In certain other configurations, the MCU may be enabled to operate without loss of safety in the absence of an RF
signal, much as a safety PLC will do. Such applications are strictly defined.
3.1.2 Radio Interference
Signals from other RF-emitting sources might interfere with the radio communication between the OCU and MCU.
If the radio link is affected by these sources, changing the RF channel or even the RF band might be necessary.
3.2
System Address
In an industrial radio remote control system, each OCU/MCU pair shares a common, unique system address. This
system address is contained in every telegram sent by the OCU and is checked by the MCU every time a RF
signal is received. The MCU processes a command only when the address in the telegram and the address
stored in the MCU match. This is a safety measure to ensure that the MCU will act only upon its assigned OCU.
The system address is stored in the TransKeys; please see Section
Figure 2: OCU TransKey (black)
