411, 611 & 325 OCU
User Manual
8
9M02-8999-A001-EN
4.1.1 Continuous Transmission
Normally transmission is continuous and the MCU uses this as part of the information required to maintain the
Main Contactor control relays in an active state. If the MCU does not receive a valid telegram in this mode for a
defined period of time, it automatically turns off, i.e. main contactor control relays and command relays open.
Depending on the application, this time varies from 0.5 s to 2.0 s.
Some MCU function relays may be maintained in the absence of communication from an OCU, an example may
be the latched lights function, there are wide range of non-crane type applications that may also continue to run
function relays in the absence of an online OCU.
Note:
In order to ensure optimum communication between the OCU and the MCU, the OCU should always
ideally be operated with line-of-sight transmission to the MCU antenna. Try to avoid total shielding of
the signal path by metallic and other solid obstructions.
4.1.2
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, it may cause intermittent operation and a changing the RF channel
might be necessary.
4.2 Telegram Security
The transmitted telegram contains several security features, as follows:
4.2.1 System Address
This system uses a 24-bit addressing scheme, normally comprising a 16 bit master-address and an 8 bit sub-
address extension, where each OCU/MCU pair shares a common, unique overall address. This address is
contained in every telegram sent by the OCU and is checked by the MCU every time an RF signal is received.
The MCU processes a command only when the address in the telegram matches its own defined address. This is
a safety measure to ensure that the MCU will act only upon its assigned OCU.
4.2.1.1
Addressing Modes
There are multiple addressing modes that may be implemented depending on the specific application needs,
these are;
TSAC mode
= 16 bit Master Address (MA) and 8 bit Sub Address (
SA
), creating one single 24 bit address.
e.g.
OCU address = 0000 0000 0000 0001
0000 0001
MCU address = 0000 0000 0000 0001
0000 0001
(MCU Online matching MA plus SA byte)
equivalent to a 24 bit address.
This mode enables an OCU
to select one of up to 255 MCUs (and request a Talkback™ message from that
MCU).
BSAC mode
= 16 bit MA and an 8 bit SA where each bit of the SA represents one of 8 possible MCUs.
e.g.
OCU Address = 0000 0000 0000 0001
0100 0101
MCU 1 Address =
0000 0000 0000 0001
0000 0001
(MCU Online matching MA plus SA bit)
MCU 2 Address = 0000 0000 0000 0001
0000 0100
(MCU Online matching MA plus SA bit)
MCU 3 Address = 0000 0000 0000 0001
0100 0000
(MCU Online matching MA plus SA bit)
equivalent to a 17 bit address.
