L-DALI User Manual
368
LOYTEC
Version 5.2
LOYTEC electronics GmbH
9.2 MS/TP (LDALI-ME204 only)
MS/TP is an RS-485 protocol and usually needs three wires (negative, positive, and
reference). Polarity must be connected correctly. When using 2-wire MS/TP, earth ground
must be connected to the negative terminal of the power supply. Never connect the positive
terminal of the power supply to earth ground! See Section 4.9.1 for wiring instructions.
Each MS/TP network segment must be properly terminated. Use an LT-04 network
terminator connected at each of the two ends of the segment media.
The RS-485 transceiver of the device represents a full-load on the RS-485 bus.
Consequently, a minimum of 31 devices are supported on the MS/TP channel. More devices
may be possible, if they represent half-load or quarter-load. Please consult the third-party
documentation. If more MS/TP devices need to be connected, use an RS-485 repeater to
separate them electrically.
Logically, the MS/TP bus supports up to 255 devices. Each MS/TP device must be assigned
a unique MAC address. Up to 127 MS/TP masters can be connected. Make sure, that the
Max_Master setting includes the highest MS/TP master MAC address.
For operation of some slower devices on the MS/TP network it is recommended to set the
following properties of the device object to fine-tune communication on the network:
APDU_Timeout = 60000 (1 min).
APDU_Segement_Timeout = 40000 (40 sec).
9.3 Redundant Ethernet (LDALI-E101-U/LDALI-E201-U only)
9.3.1 Ethernet Cabling Options
The L-DALI models LDALI-E101-U and LDALI-E201-U are equipped with two Ethernet
ports, which are connected to an internal Ethernet switch. This allows for advanced cabling
options to reduce cabling costs or to increase network resilience. For this discussion, the
term
upstream
is used to designate the direction towards the network, which the devices are
connected to. Likewise, the term
downstream
is used to designate devices more distant to
the network which the devices are connected to.
Redundant cabling options are enabled by the Rapid Spanning Tree Protocol (RSTP) which
is implemented in most managed switches. Please note, that this is a feature of the switch,
not of the L-DALI, so that LOYTEC cannot give a guarantee that this will work with a
particular switch model. In no case redundant cabling options will work with unmanaged
switches. The older Spanning Tree Protocol (STP) should not be used for this type of
application, as it converges too slowly.
Star topology
: In the most basic setup, a device is connected to an Ethernet switch with one
cable. This is called a star cabling because all devices are connected to a common upstream
device. In this setup, the cable and the switch are single point of failures.
Chain topology
: Because the L-DALI itself acts as an Ethernet switch, this device can be
connected to a chain. This is a special form of the star topology. Its advantage is the
reduced cabling costs. The disadvantage is the connection loss to downstream devices when
an upstream device is powered-off, reset or removed. Also, the Ethernet bandwidth (100
MBit/s) is shared among all members of the chain. The last device has one unused Ethernet
port, as it is not allowed to create Ethernet loops without STP. The recommended maximum
number of daisy-chained devices is 20.
