ETHERNET CHAINING NETWORK AND METHOD
The present invention is directed to a scalable, daisy chained Ethernet architecture that allows monitor modules with point-to-point connections between them to be removed from the chain and replaced (one at a time) without affecting the operation of the chain. The chain can scale from just a few modules to a large number as required.
BACKGROUND OF THE INVENTION
Aonitoring/control system should be expandable according to the number of points needed, so as to require just a few modules or many modules. Failures in one module should not affect the operation of other modules and modules should be able to be swapped out without affecting other modules. High speed communication between modules is required. In this regard, serial communication keeps pin counts low and bandwidths high, but high speed serial links (such as Ethernet) are typically point to point and require a bridge or switch circuit. This switch circuit becomes a single point failure source that can take the entire system out of operation.
In existing monitoring/control system designs, the single point failure issue has been solved using redundant networks. In the case of standard PICMG 2.16, two separate switch cards are installed into the rack holding monitor cards, providing separate Ethernet links to each monitor card. However, there are difficulties to with this approach. First, a switch card must have enough ports on it to service the full rack. For a small number of channels, the user must still purchase the two switch cards, thereby greatly increasing the buy-in cost of the rack. Second, the size of the rack is limited to the number of channels supported on the switch cards.
BRIEF DESCRIPTION OF THE INVENTION
In an exemplary embodiment of the invention, a local area network comprises a plurality of modules, each module having at least two of the plurality of modules preceding said module in the network and/or at least two of the plurality of modules following said module in the network, a plurality of links extending between the
plurality of modules, each point-to-point link extending between two modules so as to connect the plurality of modules in daisy chain fashion, each of the plurality of modules being connected by a point-to-point link to each of the two modules preceding said module and/or to each of the two modules following said module, whereby the daisy chain of modules can be extended and/or each of the plurality of modules can be removed one at a time from the network and replaced without affecting the operation of the network.
In another exemplary embodiment of the invention, an Ethernet comprises a plurality of monitors connected together in daisy chain fashion, each monitor having at least two monitors preceding said monitor in the Ethernet and/or at least two monitors following said monitor in the Ethernet, a plurality of point-to-point links extending between the plurality of monitors so as to connect said plurality of monitors in said daisy chain fashion, each point-to-point link extending between two of the plurality of monitors, each of the plurality of monitors being connected by a point-to-point link to each of the two monitors preceding said monitor in the Ethernet and/or to each of the two monitors following said monitor in the Ethernet, whereby the daisy chain of monitors can be extended and/or each of the plurality of monitors can be removed one at a time from the Ethernet and replaced without affecting the operation of the Ethernet.
hi yet another exemplary embodiment of the invention, a method of interconnecting monitor modules to form a local area network, which comprises a plurality of monitor modules and a plurality of point-to-point links extending between the plurality of monitor modules so as to interconnect the monitor modules in a daisy chain fashion, comprises the steps of connecting each of the plurality of monitor modules through point-to-point links to each of the two monitor modules preceding said monitor module in the daisy chain network, and/or connecting each of the plurality of monitor modules through point-to-point links between each of the two monitor modules following said module in the daisy chain network.
The present invention is directed to a daisy chained local area, network, such as an Ethernet, and to a method for interconnecting modules using a daisy chained local
area network architecture, such as an Ethernet. The architecture includes point-to-
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point connections between each module and the two modules in the chain preceding and following such module. This architecture allows the chain to be extended, and for modules to be removed from the chain without interrupting service to the other modules. A microprocessor and additional port provide an additional gateway for connection to an external device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a block diagram showing the chaining architecture of the present invention for monitors that are part of an Ethernet.
FIGURE 2 is a block diagram showing the internal electrical components of each monitor used in the chaining architecture of the present invention shown in FIGURE 1.
DETAILED DESCRIPTION OF THE INVENTION
A local area network or "LAN" is a data communications network that is geographically limited. Typically, a LAN allows the easy interconnection of computers, monitors, terminals, printers and the like within adjacent buildings. An Ethernet is one example of a LAN in which data is broken into packets, with each packet being transmitted using a CSMA/CD algorithm until it arrives at its destination without colliding with any other packet. Thus, in operation, each node in the LAN is either transmitting or receiving data packets at any instant of operation.
The present invention uses a daisy chained Ethernet architecture 10 shown in Figure 1 in which a plurality of monitor modules 12 are daisy chained together using a plurality of point-to-point links 14 extending between modules 12. In the daisy chained Ethernet architecture 10 shown in Figure 1, each monitor module 12 is linked to each of the two modules preceding it in the Ethernet and to each of the two modules following it in the Ethernet.
Referring to Figure 1, there is shown an Ethernet in which five monitors 12, numbered 1 through 5, are linked together using the daisy chained Ethernet
architecture 10 of (he present invention. In the daisy chained Ethernet architecture of the present invention, monitor 3, for example, is daisy chain linked to monitors 1 and 5 and monitors 2 and 4 by a plurality of point-to-point links 14, which are typically Ethernet cables. Monitors 1 and 2 precede monitor 3 in the Ethernet daisy chain, while monitors 4 and 5 succeed monitor 3 in the Ethernet daisy chain. In this arrangement, monitor 3 is connected to preceding monitor 1 through a first link 14a, and to preceding monitor 2 through a second link 14b. Similarly, monitor 3 is connected to following monitor 5 through a third link 14c, and to following monitor 4 through a fourth link 14d.
Similar connecting arrangements are used to connect monitors 1, 2, 4 and 5 to the other monitors included in the Ethernet daisy chain 10 shown specifically in Figure 1. Thus, for example, where only a single monitor, i.e., monitor 1, precedes monitor 2 in the Ethernet, while two monitors, i.e., monitors 3 and 4, succeed monitor 2 in the Ethernet, monitor 2 is connected to monitor 1 through a fifth link 14e, to monitor 3 through second link 14b, and to monitor 4 through a sixth 14f. Likewise, where no monitor precedes or succeeds a monitor, e.g., monitors 1 and 5, in the Ethernet, such monitor will be connected only to the two monitors that either precede or succeed it in the Ethernet. Thus, for example, monitor 1 is connected only to monitor 2 through first link 14a, and to monitor 3 through second link 14b.
In the daisy chain Ethernet arrangement of the present invention, any one of the modules 12 may be removed without breaking the communication path between the other modules. Thus, for example, if monitor 3 is removed from the Ethernet, monitor 5 will still be able to communicate with monitor 1 via monitors 4 and 2 and the links 14g connecting monitor 5 and monitor 4, 14f connecting monitors 4 and 2, and link 14e connecting monitors 2 and 1.
It is clear from the preceding discussion that the daisy chain Ethernet 10 shown in Figure 1 can be scaled from just a few modules 12, such as the monitor 1 to 5 shown in Figure 1, to a large number of modules 12, as required. Where the daisy chain Ethernet 10 is expanded, the architecture of the daisy chain Ethernet 10 will, nevertheless, include point-to-point connections between each additional module and
the two modules in the chain preceding the module and the two modules in the chain following such module.
Referring now to Figure 2, each monitor 12 also includes a microprocessor 16 and an Ethernet 1C 18, connected through a bus 20 to microprocessor 16, for connection to external devices outside the chain, such as a control system or HMI, through an Ethernet link 22 connected to Ethernet 1C 18. The microprocessor 16 provides a gateway, filtering off internal rack messages or changing between internal and external protocols. Also connected to microprocessor 16 through another bus 24 is a multi-port switch integrated circuit 26, which controls the receipt and transmission of data packets from one module to another. Thus, in the example of monitor 3, multiport switch 26 would be connected to point-to-point links 14a to 14d to transfer data packets through monitor 3 from monitors 1 and/or 2 to monitors 4 and/or 5, and vice versa. To prevent data looping through the redundant Ethernet networks, the switch hip utilizes IEEE 802. Id Spanning Tree Protocol, or an equivalent.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

CLAIMS:
1. A local area network comprising:
a plurality of modules, each module having at least two of the plurality of modules preceding said module in the network and/or at least two of the plurality of modules following said module in the network,
a plurality of links extending between the plurality of modules, each point-to-point link extending between two modules so as to connect the plurality of modules in daisy chain fashion,
each of the plurality of modules being connected by a point-to-point link to each of the two modules preceding said module and/or to each of the two modules following said module, whereby the daisy chain of modules can be extended and/or each of the plurality of modules can be removed one at a time from the network and replaced without affecting the operation of the network.
2. The local area network of claim 1, wherein each module includes a multi-
port switch for receiving data from the two modules preceding said module and/or for
transmitting data to the two modules following said module.
3. The local area network of claim 1, further comprising at least one
additional module, each additional module including point-to-point connections
between the two modules in the network preceding said additional module and/or the
two modules in the chain following said additional module.
4. The local area network of claim 1, wherein each module is a device
selected from the group consisting of a monitoring device for rotating machines, a
control device for rotating machines, and a data acquisition for rotating machines.
5. The local area network of claim 1, wherein each module is a device
selected from the group consisting of a computer, a monitor and a terminal.
6. The local area network of claim 1, wherein each module includes a
controller and a link for connection to external devices outside the network.
7. The local area network of claim 6, wherein the controller is a device
selected from the group consisting of a microprocessor, a network processor, a field
programmable gate array ("FPGA"), a digital signal processor, an Ethernet router and
additional switch chips.
8. An Ethernet comprising:
a plurality of modules connected together in daisy chain fashion, each module having at least two modules preceding said module in the Ethernet and/or at least two modules following said module in the Ethernet,
a plurality of point-to-point links extending between the plurality of modules so as to connect said plurality of modules in said daisy chain fashion, each point-to-point link extending between two of the plurality of modules,
each of the plurality of modules being connected by a point-to-point link to each of the two modules preceding said module in the Ethernet and/or to each of the two modules following said module in the Ethernet, whereby the daisy chain of modules can be extended and/or each of the plurality of modules can be removed one at a time from the Ethernet and replaced without affecting the operation of the Ethernet.
9. The Ethernet of claim 8, wherein each module includes a multi-port switch
for linking to the two modules preceding said module in the Ethernet and/or for
linking to the two modules following said module in the Ethernet.
10. The Ethernet of claim 8, further comprising at least one additional
module, each additional module including point-to-point connections between the two
modules in the network preceding said additional module and/or the two modules in
the chain following said additional module.
11. The Ethernet of claim 8, wherein each module is a device selected from
the group consisting of a monitoring device for rotating machines, a control device for
rotating machines, and a data acquisition for rotating machines.
12. The Ethernet of claim 8, wherein each module is a device selected from
the group consisting of a computer, a monitor and a terminal.
13. The Ethernet of claim 8, wherein each module includes a controller and a
link for connection to external devices outside the Ethernet.
14. The Ethernet of claim 13, wherein the controller is a device selected from
the group consisting of a microprocessor, a network processor, a field programmable
gate array ("FPGA"), a digital signal processor, an Ethernet router and additional
switch chips.
15. A method of interconnecting modules to form a local area network
comprising a plurality of modules and a plurality of point-to-point links extending
between the plurality of modules so as to interconnect the modules in a daisy chain
fashion, the method comprising the steps of:
connecting each of the plurality of modules through point-to-point links to each of the two monitor modules preceding said module in the daisy chain network, and/or
connecting each of the plurality of modules through point-to-point links between each of the two modules following said module in the daisy chain network.
16. The method of claim 15 further comprising the steps of providing at least
one additional module in the network, and connecting each additional module through
point-to-point connections between the two modules in the network preceding said
additional module and/or the two modules in the chain following said additional
module.
17. The method of claim 15, wherein each module is a device selected from
the group consisting of a monitoring device for rotating machines, a control device for
rotating machines, and a data acquisition for rotating machines.
18. The method of claim 15, wherein each module is a device selected from
the group consisting of a computer, a monitor and a terminal.
19. The method of claim 15 further comprising the step of providing each
module with a controller and a link for connection to external devices outside the
network.
20. The method of claim 19, wherein the controller is a device selected from the group consisting of a microprocessor, a network processor, a field programmable gate array ("FPGA"), a digital signal processor, an Ethernet router and additional switch chips.