Level Plus
®
LevelLimit
®
Operation Manual
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17
I
7.3 Industrial topologies
There are four topologies described and illustrated below. However,
the daisy chain topology is not recommended by MTS.
The topologies are shown for the Modbus communication of the level
transmitter. MTS recommends running independent cable runs for
each HI Level Switch in the network.
Point-to-point
The point-to-point topology consists of having only one device on the
loop as shown in Fig. 91. This topology is not usually used with a bus
network since it does not take advantage of placing multiple devices
on a loop.
Bus with spurs
The bus with spurs topology has a main trunk cable that has each
PLC
Fig. 9: Point-to-point topology
Fig. 10: Bus with spurs topology
device connected via its own spur at a junction box as shown in Fig.
102. The bus with spurs and tree topologies can also be used together
to form a hybrid topology.
Tree alignment
The tree topology is very similar to the bus with spurs topology with
PLC
7. Electrical connections
7.1 Basic information
A typical intrinsically safe connection for the Level Plus
®
LevelLimit
®
transmitter includes protective safety barriers, a power supply and a
reading or monitoring device. Refer to Agency information in chapter
13.
A typical Explosionproof/flame proof connection for the Level Plus
®
LevelLimit
®
transmitter includes a power supply and a reading or
monitoring device. All cabling is in approved conduit with sealoffs
as specified by local electrical code. Refer to agency information in
chapter 13.
7.2 Safety recommendations
Be sure to:
1. Always follow applicable local and national electrical codes and
observe polarity when making electrical connections.
2. Never make electrical connections to the LevelLimit
®
transmitter
with power turned on.
3. Make sure that no wire strands are loose or sticking out of
the terminal block connection which could short and cause a
problem.
4. Make sure that no wire strands, including shield, are in contact
with the electronic module enclosure.
5. The electronics module enclosure is grounded through internal
circuitry and is electrically isolated from the explosionproof
housing.
