Claims:1. An automatic configuration mechanism of plurality of expansion modules in a daisy chain, said mechanism comprising:
a main module,
the plurality of expansion modules adapted to connect to said main module;
the main module adapted to send a query with a broadcast device id and a configuration id to the expansion module, wherein the query comprises the broadcast id, the configuration id, data length, data, and a checksum;
the main module adapted to instruct the expansion module to assign the device id, and/or to append the device information to the query ;
the expansion module adapted to parse the query to find position from the main module by checking the data length in the received query thereafter appending the device id and information to the query and sending it to next expansion module without having instruction from main module;
the expansion module adapted to wait for a predetermined period for receiving response on the query from the next expansion module after sending the query to the next expansion module;
the main module adapted to receive the response from the expansion module; and
the main module adapted forparsing the data, extracting information on number of expansion modules operatively connected, and storing the information.

2. The mechanism as claimed in claim 1, wherein the plurality of expansion modules adapted to connect to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module.

3. The mechanism as claimed in claim 1, wherein the expansion module is adapted to wait for a predetermined period is a product of subtraction of number of expansion modules to a current expansion module and an expansion module response time.

4. The mechanism as claimed in claim 1, wherein the expansion module is adapted for sending the response to an upstream module if a current expansion module receives the response from a downstream expansion module; declaring the current expansion module as a last expansion module and sending response to the upstream module if the response is not received from the downstream expansion module.

5. The mechanism as claimed in claim 1, wherein the device information comprises the device id, type of the device and the like.

6. An automatic communication mechanism of plurality of expansion modules in a daisy chain, said mechanism comprising:
a main module;
the plurality of expansion modules adapted to connect to the main module;
the main module adapted for sending data with a single query to the plurality of expansion modules,
wherein the single query selectively comprises a broadcast id, a control byte, total data length, device id of expansion module (X), data length of device id ‘X’ data of device id “X”, device id of expansion module (Y), data length of device id ‘Y’ data of device id “Y”, device id of expansion module (N), data length of device id ‘N’ data of device id “N” and a checksum;
wherein the main module adapted for reserving the control byte in the single query for a corresponding device id; wherein the main module adapted for appending data of the plurality of expansion modules into a single data frame sequentially;
wherein the reserved control byte adapted for identifying if the single query has any data corresponding to the expansion module.

7. The mechanism as claimed in claim 6, wherein , wherein the plurality of expansion modules adapted to connect to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module.

8. An automatic configuration and communication system of plurality of expansion modules in a daisy chain, said system comprising:
a main module;
a plurality of expansion modules defined as a first expansion module, a second expansion module and N number of expansion modules;
wherein the plurality of expansion modules operatively connected to the main module;
wherein each expansion module sending information about corresponding device id of the expansion module, type of the expansion module to the main module; and
wherein the main module operatively acquiring information about the expansion module through a single query.

9. The mechanism as claimed in claim 8, wherein the plurality of expansion modules operatively connected to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module.

10. The mechanism as claimed in claim 8, wherein the main module adapted to send data to plurality of expansion modules with single query selectively comprising a broadcast id, a control byte, total data length, device id of expansion module (X), data length of device id ‘X’ data of device id “X”, device id of expansion module (Y), data length of device id ‘Y’ data of device id “Y”, device id of expansion module (N), data length of device id ‘N’, data of device id “N” and a checksum.
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to protection devices, and more particularlytechnique of automatically configuring the expansion modules used in protection devices along with an efficient communication mechanism.

BACKGROUND

[002] Protection systems which employ modular units for attaching to a main controlling unit to increase their functionality are gaining popularity due to their modular design. Moreover, with the increasing need for protection features, there is a need to design a technique that permits the expansion units to be easily added to an existing protection relay system.

[003] Daisy chain latency is being a critical issue in systems with multiple modules in a connection. The time required for traversing from one module to another further increases due to the processing time of the query within the module before transmission to the next device.

[004] US 7228373 B2 entitled “Serial digital communication system and method” discloses a communication system includes a master device which communicates with a chain of serially-connected slave devices. The master originates messages, each of which is intended for a particular ‘target’ slave device. Each message contains a ‘distance to target device’ value equal to the number of devices between the master and target, and a data packet containing data to be conveyed between the master and target. Each slave device determines if the ‘distance to target device’ value indicates that it is the target. If not, the slave device increments or decrements the value in real time, with no latency, and transmits the modified message to the next slave device until received by the target device. In one embodiment, the target device may place data in the data packet, and the slave devices are arranged to buffer the data back to the master device.
[005] US 7565470 B2 entitled “Serial bus device with address assignment by master device” discloses a daisy chain serial bus system. For bus construction, the slave device has a first data transmission port to transfer serial data with its upward connected device and a second data transmission port to transfer serial data with its downward connected device. The most upward slave device is connected to a master device. In each slave device, the input data from a first data transmission port is transferred to a data input gate in a second data transmission port. There is a control register in each slave device to control the data input gate of the second data transmission port. After the bus system has been started, only the slave device connected to the master device can receive the data from the master device, so that the master device can assign the first device address to the slave device connected to it, then, the master device can assign the second device address to the slave device next connected to the first slave device on the bus. By this way, the master device can assign the device address to each slave device on the bus one by one.
[006] US 6799235 B2 entitled “ Daisy chain latency reduction” discloses transmitting data on a serial data transmission path to reduce latency including reading only enough of a device address of a serial data word to determine if the serial data word is addressed to a first device having an address, wherein the serial data word is transmitted across a first link of a first serial data transmission path to the first device and passing the serial data word across a second link of the first serial data transmission path to a second device if the serial data word is not addressed to the first device.
[007] US 9294300 B2entitled “Token based communication in daisy chain configured battery management devices” discloses a battery management and protection system includes a string of battery management and protection integrated circuit devices that may be connected to one another in a daisy chain configuration. Some of the devices can be electrically connected to one or more battery cells. Each device includes an inter-device communication interface comprising a daisy chain line driver. The system includes a controller external to the string of devices and a bi-directional connection lines connecting each device in the string to an upstream and/or downstream device in the string. The system can allow the external controller to access any single one of the devices in the daisy chain, any subset of the devices in the daisy chain, or all the devices in the daisy chain using a single command that is transmitted from one device to the next over a bi-directional connection line.
[008] US 20070088884 A1 entitled “Dynamic master/slave configuration for multiple expansion cards” discloses a computing system having expansion modules. One of the expansion modules is identified as a master module. The other modules act as slaves to the master module. The central processing unit routes a task to either the master module for portioning out or to all of the expansion modules. The master module then receives completion signals from all of the active slave modules and then provides only one interrupt to the central processing unit for that task.
[009] The problems in the existing art are that reduces latency by only checking the device address of the received query and passing it ahead if it does not match, identifies the devices using multiple queries, the master have to send prior information about the ‘distance to target’ and also about the number of modules connected in the chain.
[0010] Thus, there is a need to develop an automatic configuration and communication mechanism of expansion modules in a daisy chain to overcome the problems in the existing technology. In the present invention, the master does not have to send prior information about the ‘distance to target’ nor about the number of modules connected in the chain. The devices can self-assign the Device IDs to themselves by analyzing the previously received frame. In the present invention, the devices can be configured using just a single query, which can carry data of multiple modules which further makes the communication faster. In the present invention, the latency is further reduced by simultaneously sending the query ahead without processing it before transmission.

SUMMARY

[0011] This summary is provided to introduce concepts related toan automatic configuration and communication mechanism of expansion modules in a daisy chain, and the same are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[0012] According to first aspect of the present invention, there is provided anautomatic configuration mechanism of plurality of expansion modules in a daisy chain, said mechanism comprising: a main module; the plurality of expansion modules adapted to connect to a main module;the main module adapted to send a query with a broadcast device id and a configuration id to the expansion module, wherein the query comprises the broadcast id, the configuration id, data length, data, and a checksum;the main module adapted to instruct the expansion module to assign the device id, and/or to append the device information to the query ;the expansion module adapted to parse the query to find position from the main module by checking the data length in the received query thereafter appending the device id and information to the query and sending it to next expansion module without having instruction from main module; the main module adapted to instruct the expansion module to send the query to next expansion module; the expansion module adapted to wait for a predetermined period for receiving response on the query from the next expansion module after sending the query to the next expansion module;the main module adapted to receive the response from the expansion module; andthe main module adapted for parsing the data, extracting information on number of expansion modules operatively connected, and storing the information.
[0013] In the first implementation of the first aspect of the present invention
in the mechanism as described above wherein the plurality of expansion modules adapted to connect to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module.

[0014] In the second implementation of the first aspect in the mechanism as described above, the expansion module is adapted to wait for a predetermined period is a product of subtraction of number of expansion modules to a current expansion module and an expansion module response time.
[0015] In the third implementation of the first aspect in the mechanism as described above, the expansion module is adapted for sending the response to an upstream module if a current expansion module receives the response from a downstream expansion module; declaring the current expansion module as a last expansion module and sending response to the upstream module if the response is not received from the downstream expansion module.
[0016] In the fourth implementation of the first aspect in the mechanism as described above, the device information comprises the device id, type of the device and the like.
[0017] According to the second aspect of the present invention, there is provided anautomatic communication mechanism of plurality of expansion modules in a daisy chain, said mechanism comprising: a main module; the plurality of expansion modules adapted to connect to the main module;the master module adapted for sending a single query to the plurality of expansion modules, wherein the single query comprises a broadcast id, a control byte, total data length, device id of expansion module (X), data length of device id ‘X’ data of device id “X”, device id of expansion module (Y), data length of device id ‘Y’ data of device id “Y”, device id of expansion module (N), data length of device id ‘N’ data of device id “N” and a checksum; wherein the main module adapted for reserving the control byte in the single query for a corresponding device id; wherein the main module adapted for appending data of the plurality of expansion modules into a single data frame sequentially ;wherein the reserved control byte adapted for identifying if the single query has any data corresponding to the expansion module.
[0018] In the first implementation of the second aspect of the present invention
in the mechanism as described above wherein the plurality of expansion modules adapted to connect to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module.
[0019] According to the third aspect of the present invention, there is provided anautomatic configuration and communication system of plurality of expansion modules in a daisy chain, said system comprising:a main module;a plurality of expansion modules defined as a first expansion module, a second expansion module and N number of expansion modules;wherein the plurality of expansion modules operatively connected to the main module;wherein each expansion module sending information about corresponding device id of the expansion module, type of the expansion module to the main module; andwherein the main module operatively acquiring information about the expansion module through a single query.
[0020] In the first implementation of the third aspect of the present invention
in the mechanism as described above wherein the plurality of expansion modules adapted to connect to the main module, said expansion module comprising:
one port of the expansion module is adapted to connect to either the main module or the upstream expansion module; and
another port of the expansion module is adapted to connect to the downstream expansion module
[0021] In the second implementation of the third aspect of the present invention in the mechanism as described above the main module adapted to send data to plurality of expansion modules with single query selectively comprising a broadcast id, a control byte, total data length, device id of expansion module (X), data length of device id ‘X’ data of device id “X”, device id of expansion module (Y), data length of device id ‘Y’ data of device id “Y”, device id of expansion module (N), data length of device id ‘N’, data of device id “N” and a checksum.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
[0022] The detailed description is described with reference to the accompanying figures. In the figures, the digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.
[0023] Figure 1illustratesautomatic configuration and communication mechanism of expansion modules in a daisy chain.
[0024] It is to be understood that the attached drawings are for purposes of illustrating the concepts of the invention and may not be to scale.
[0025] DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0026] The following clearly describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0027] A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.
[0028] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components, modules, units and/or circuits have not been described in detail so as not to obscure the invention.
[0029] Although embodiments of the invention are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.
[0030] Referring to the Fig1, the main module (10) here is the protection device with control function. It acts as a master for the expansion units (salves) (11,12,13,14). Each expansion module has two bi directional ports (20,21). The main module (10) (master) is connected to the first expansion module; the other end of the first expansion module is connected to the next expansion module and so on (up to the maximum number of modules permitted).
[0031] The communication from Main unit (master) to the Expansion modules (slaves) is termed as downstream communication (15, 16) and from Expansion modules to Main unit as upstream communication (17,18).
[0032] The modules need to be configured before the serial communication with a particular expansion or multiple expansion modules is possible. Thus the scheme here is divided into two phases namely:
[0033] Configuration phase: Here each expansion module assigns itself a Device Id and sends information about the device identifiers and respective types of modules connected to the main module.
[0034] Serial data communication: Here the master sends queries to control or get data from one or more expansion modules.
[0035] Configuration phase:
[0036] For easily addition of an expansion module there is a need for an automatic recognition of the modules. The present invention discloses the method of configuring multiple expansion modules (Digital Input /Output Modules, Temperature Sensing module, Analog input/ output modules, Earth fault modules) connected in a daisy chain fashion to the main module. The maximum number of modules permitted is to be predefined based on the application. The current embodiment permits maximum 5 modules to be connected in the daisy chain. As the number modules increases the communication time from main unit to expansion increases. It is therefore essential to limit the number of modules based on the time criticality of the system. The expansion modules connected are of different types and it is necessary for the main module to identify the type of the expansion modules connected. This can be accomplished without a need for external pins or synchronization using the following scheme.
[0037] 1. On power on of the system, the Main unit (MU), which is the master, sends a query with broadcast device Id and the CONFIG_ID command byte which tells the expansion module to assign itself an device Id and append it’s device information (Device Id, type, etc.) to the query frame and send it further to the next port where the next expansion module is connected.
Query Format:
BROADCAST_ID CONFIG_ID_CMD DATA_LEN DATA checksum

[0038] 2. When the expansion module receives above query, it parses the data frame to check it’s data length to find is position from master (MU), for example:
a. If the data length is zero then Expansion module will assign DEV_ID_1 to itself, and append the device information with device ID in the received query frame and sends to next expansion module.
b. If the data length is (2 x Device information size), then expansion module will assign DEV_ID_3 to itself, and append the device information with device ID in the received query frame and sends to next expansion module.

[0039] 3. After sending above frame to downstream Expansion module, Current expansion module will wait for the same query response from downstream expansion module for a time (Max Modules permitted – Current expansion module ID) x Expansion module response time.
[0040] 3. After sending above frame to downstream Expansion module, Current expansion module will wait for the same query response from downstream expansion module for a time (Max Modules permitted – Current expansion module ID) x Expansion module response time.
[0041] 4. If no response is received from the downstream module it will declare itself as the last module in the chain and send the same query which it had sent downstream back on the upstream side as response.
[0042] 5. If the response is received from the downstream module, then the current module will forward it upstream till it reaches the master.
[0043] 6. When the master receives the response, it will parse the data frame and extract information about the number of modules connected along with their Device Ids and respective device information and stores it for further communication.
[0044] This invention helps the main unit to get the complete knowledge about the count and details of the expansion modules along with their respective device identifiers connected to it. Also, in future, an inter expansion modules communication can be set because each expansion module has information about the identifiers and types of all other modules connected in the chain.
[0045] Serial Data Communication Phase:
[0046] For an efficient serial communication, it is essential to reduce latency in the daisy chain. Checking every query for its address and matching it with its own address adds a lot of delay till the query reaches the destination module. With this in view the all the queries received from the upstream modules are passed to the downstream modules simultaneously without initial processing to avoid the latency in transmission.
[0047] Also this invention helps the master to send information to multiple modules by sending just a single query downstream. This can be done by reserving a byte in the frame for device identification. The master appends the data message of multiple expansion modules onto a single data frame sequentially. The reserved control byte helps the expansion module to identify if the query has any data corresponding to it. After passing the query downstream, the expansion module analyses the frame to extract information (corresponding to its DEV_ID). The checksum at the end of the frame helps in identifying the data for its correctness.
[0048] For example: if there are 4 expansion modules connected to the master. And the query has data pertaining to the second and fourth expansion module then, the second and fourth bits of the control byte are SET. When this frame is received by the expansion modules they check if the bit corresponding to their location/DEV_ID is SET. If that bit is found to be SET, the frame is parsed till it finds the data corresponding to its DEV_ID. If the bit corresponding to its location is not SET it simply discards the frame.

[0049]

[0050] This is how sending multiple queries every time when data corresponding to multiple modules has to be sent is avoided in this technique. The communication becomes faster, also because the query is first passed to the downstream modules and then processed which greatly reduces the latency time of the query from the master to the slaves farther in the chain.
[0051] The present invention reduces the latency which ensures that the processing time of the module does not add up to the latency due to traversing in the daisy chain. The presented invention set up an inter expansion module communication as all the expansion modules are aware of the identifiers and types of modules connected along the chain for future application.
[0052] The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. An automatic configuration and communication mechanism of expansion modules in a daisy chain as described above does not limit the scope of the present invention. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.
[0053] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.
[0054] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.