Mantracourt B24, B24-SSBX-A Technical Manual

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B24 Telemetry Technical Manual

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B24

Bluetooth Telemetry System

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

Introduction / Overview .............................................................................................................................................3

Advertising Operation ............................................................................................................................................................................... 3

Connected Operation ................................................................................................................................................................................ 3

B24 Advert Format ......................................................................................................................................................4

Local Name .................................................................................................................................................................................................... 4

Manufacturer Specific Data .................................................................................................................................................................... 4

Format ID ................................................................................................................................................................................................... 4

Status .......................................................................................................................................................................................................... 4

Units ............................................................................................................................................................................................................. 5

Data Tag ..................................................................................................................................................................................................... 5

Data.............................................................................................................................................................................................................. 5

Bluetooth Connected Mode ......................................................................................................................................6

Telemetry Configuration Service .......................................................................................................................................................... 6

Data Rate ................................................................................................................................................................................................... 6

Resolution ................................................................................................................................................................................................. 6

Battery Threshold ................................................................................................................................................................................... 7

View PIN ..................................................................................................................................................................................................... 7

Serial Number .......................................................................................................................................................................................... 7

Battery Value ............................................................................................................................................................................................ 7

System Zero .............................................................................................................................................................................................. 7

Configuration Pin ................................................................................................................................................................................... 8

Model Name ............................................................................................................................................................................................ 8

Firmware Version .................................................................................................................................................................................... 8

Telemetry Data Service ............................................................................................................................................................................. 9

Data Value ................................................................................................................................................................................................. 9

Data Units .................................................................................................................................................................................................. 9

Telemetry Calibration Service ............................................................................................................................................................. 10

Sensitivity Range ................................................................................................................................................................................. 10

Coefficient (@Index)........................................................................................................................................................................... 10

Linearisation Index .............................................................................................................................................................................. 10

Linearisation Repeat ........................................................................................................................................................................... 10

Linearisation Points ............................................................................................................................................................................ 11

Base Value .............................................................................................................................................................................................. 11

Base Units ............................................................................................................................................................................................... 11

Data Gain ................................................................................................................................................................................................ 11

Data Offset ............................................................................................................................................................................................. 11

Calibration PIN ..................................................................................................................................................................................... 11

Calibration Units .................................................................................................................................................................................. 11

Advanced Index ................................................................................................................................................................................... 12

Advanced Data ..................................................................................................................................................................................... 12

Connection Security ................................................................................................................................................................................ 12

Operation Examples ................................................................................................................................................. 13

Decoding Data with View PIN ............................................................................................................................................................. 13

Connection ................................................................................................................................................................................................. 14

Reading Data ............................................................................................................................................................................................. 14

Examples: ................................................................................................................................................................................................ 14

Writing Data ............................................................................................................................................................................................... 15

Calibration .................................................................................................................................................................................................. 16

Unit Conversion ........................................................................................................................................................................................ 18

Appendices ................................................................................................................................................................ 19

Appendix A - Bluetooth UUID Quick Reference .......................................................................................................................... 19

Appendix B - Units .................................................................................................................................................................................. 20

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendix C - Advanced Parameters ................................................................................................................................................ 23

Appendix D – Filter .................................................................................................................................................................................. 25

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

Introduction / Overview

The B24 Bluetooth Telemetry range provides access to quality measurements on a mobile platform such as a

phone or tablet. The delivery mechanism is ‘Bluetooth Low Energy’ (Also known as ‘Bluetooth Smart’ or BLE)

which utilises the flexibility and availability of Bluetooth receivers while maintaining the low power requirements of embedded systems. B24 is built upon two complimentary principles of BLE, broadcast advertising data which enables users to deliver the same data to multiple receivers simultaneously and low power connections which can be used in a point to point system. B24 is available in OEM bare board formats and with environmentally sealed enclosure with integrated battery holder. This manual provides details of data delivery and configuration mechanisms available to system developers intending to implement their own configuration and monitoring application. There are also worked examples for calibration, data delivery and unit conversion.

Advertising Operation

The advertising mode of operation enables B24 modules to broadcast measurement data to multiple locations without retransmission. The advert is a new operational mode within ‘Bluetooth Low Energy’ and facilitates the delivery of data without a connection. This mode of operation is useful in ‘many to many’ and ‘one to many’ use cases.

Connected Operation

The connected operational mode enables Bluetooth Low Energy devices to connect directly to the B24 module. A single mobile device can be connected to multiple B24 transmitter modules simultaneously. This mode has a dual purpose as it may be used to monitor data and configure the device. When it is used for the delivery of data the application can register to receive notification updates when the status and engineering unit value changes. This mode of operation is useful in ‘one to one’ and ‘many to one’ use cases.

One to One

Many to One

One to Many

Many to Many

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

B24 Advert Format

The Bluetooth advert is the primary operating role of this product. The advertising packet is broadcast periodically at a configurable rate. The full list of configurable items will be discussed with the section on the

Bluetooth Connected Mode section.

The transmission of the advert and the corresponding data is also split into subtopics. The Bluetooth Special Interest Group has provided specific details on the format and content of each advert type. The B24 advert is constructed from the connection flags (advert type 0x01), manufacturer specific data (advert type 0xFF) and the device local name (advert type 0x09). Provision has been made for future developments and extensions of the manufacturer specific data to include other data formats but for the moment only one will be discussed.

The basic format and structure of the B24 advert packet can be observed using a simple BLE scanner. There are many available for android and Apple iOS (A good example is the nRF Connect app).

Local Name

The local name is part of the standard set of data defined by the Bluetooth SIG. The module name that is supplied will depend upon the length of the name given to the product. The length of the name has an impact upon the rest of the data packet and as such should be kept short where possible. The advert is sent with advert type 0x09 as an ASCII character array. The local name is factory configured to the default value “B24”. The name field in the device has a maximum length of eight characters. The advert mechanism will send the full name of the device stored in the EEPROM.

Manufacturer Specific Data

The manufacturer specific data is sent with advert type 0xFF. The current format carries data for a single sensor. The format of this section is shown in Table 1. By default a hash is applied to the data broadcast from the unit and this will be applied to all bytes after the first data tag pair (Shown in bold). An example decoding the advert is provided later in this section. The measured data is a fixed length parameter in the advert of 4 bytes. This will follow the standard Float format (IEEE 754). N.B The status byte, units, data and the terminating data tag pair are encoded. N.B The format shown in Table 1 is indicative of the bytes transmitted. Some monitoring applications and APIs do not present the length field to the user.

Name

Size

Description

Length field

1 byte

Part of the Spec

Advert Type

1 byte

0xFF (Manufacturer Specific Data)

Company ID

2 bytes

0x04C3

Format ID

1 byte

Data Tag

2 bytes

Module ID

Status

1 byte

Units

1 byte

Data

4 bytes

Floating point data (IEEE 754)

Data Tag

2 bytes

Used to verify decoding

Data Tag

2 bytes

Used to verify decoding

Table 1: B24 Advert Format

Format ID

The format ID uniquely identifies the format of the rest of the packet. This allows for future expansion of the format for other purposes without impacting legacy equipment. This is currently set to 1.

Status

The status byte indicates status using the bit values and is defined in Table 2.

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Bit

Name

Description

Reserved

Digital Input

Digital Input Active Flag

Batt Low

Low battery warning flag

Fast Mode

Unit is currently operating in “Fast” data rate mode.

OverRange

Input is out of sensitivity or display range

NotGross

A tare value has been applied.

Integrity

Sensor integrity Error

Shunt Cal

Shunt Cal active

Table 2: Status Byte format.

Units

The units for the module are sent as a single byte. The definition of these groups and values is in Appendix B -

Units. This table identifies the group within which a simple translation can be applied and the symbol that should

be displayed on the screen. It also includes the conversion factors that may be used to convert within a group.

Data Tag

The Data tag is defined as a 2 byte hexadecimal number. This number is specific to the sensor and configurable in the unit. The default value is assigned in the factory prior to shipping and indicated on the label. The data tag is repeated in the transmission packet in order to facilitate the extraction of the encoded data. Please refer to the

Error! Reference source not found.section.

Data

The data is a fixed length field of four bytes. All data is transmitted as a standard Float format (IEEE 754).

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Bluetooth Connected Mode

The B24 profile provides access to services and characteristics used to configure and receive measurements. They are all custom 128-bit Unique ID’s. The only generic profiles that will be enabled in the module are the mandatory Generic Access and Generic Attribute profiles. Please refer to documentation supplied by the Bluetooth SIG (Special Interest Group) for a description of the characteristics provided by these services. All the data carried over Bluetooth is received by the host application as a byte array. The data format on a read is described in Appendix A.

It is recommended that all writes to characteristics use the Write With Response method

rather than Write With No Response. This allows time for indexed characteristics to update internally.

Telemetry Configuration Service

The telemetry Configuration service provides access to general configuration parameters. The characteristics within this service are likely to be required by technicians and installers. This service is identified by its unique 128-bit ID. This is: a970fd30-a0e8-11e6-bdf4-0800200c9a66

Data Rate

The data rate defines the period between taking a measurement. The advert broadcast is also linked to this parameter. The data rate is specified in ms as the period between measurements. The value entered may be between 0 and 10000. N.B. Bluetooth does not allow adverts to be broadcast more often than every 80 ms. As such, values between 1 and 79 will be accepted as a value of 80. A value of 0 will stop data acquisition. However it will not stop the advertising profile. The adverts will be broadcast once every 5 seconds with a value of NaN and the status byte will be set to 0xFF (255 decimal). This characteristic is identified by its unique 128-bit ID. This is: a970fd31-a0e8-11e6-bdf4-0800200c9a66

Resolution

The number of samples used to produce a measurement is configurable. The resolution that can be achieved is given in Table 3. The number of samples used to obtain a measurement will directly impact upon the battery life of the product as it changes the time required to make a measurement. The measurement time is the time that the Strain Bridge input is being sampled. If the Data Rate is set to less than 200mS then the Resolution parameter is limited to a maximum of 16.

Resolution Parameter

Bits Noise Free @ 2.5 mV/V

Measurement time

Effect on Battery Life 8 (default)

14.25

20 ms

Maximum

15.25

32 ms

75%

56 ms

50%

16.5

80 ms

37%

16.75

104ms

30%

Table 3: Resolution Table.

This characteristic is identified by its unique 128-bit ID. This is: a970fd32-a0e8-11e6-bdf4-0800200c9a66

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Battery Threshold

The battery threshold value is a floating point number specified in volts. The default value (2.5 V) is designed for use with a pair of alkaline cells. The minimum operating voltage is 2.3 V. This characteristic is identified by its unique 128-bit ID. This is: a970fd33-a0e8-11e6-bdf4-0800200c9a66

View PIN

The View PIN is used to encode the broadcast data such that other users are not able to decode and read the values. This is applied on top of the normal encoding and allows the user to hide individual systems. The View PIN is an array of four characters. The full description of the usage of the data in this characteristic is given in the

Operation Examples section titled Decoding Data with View PIN.

This characteristic is identified by its unique 128-bit ID. This is: a970fd34-a0e8-11e6-bdf4-0800200c9a66

Serial Number

The serial number is set in the factory and cannot be changed by the user. This characteristic is identified by its unique 128-bit ID. This is: a970fd35-a0e8-11e6-bdf4-0800200c9a66

Data Tag

The data tag is used to identify the transmitter. It is set in the factory and indicated on the label. The parameter is writable and as such may be set to any 32 bit number. This characteristic is identified by its unique 128-bit ID. This is: a970fd36-a0e8-11e6-bdf4-0800200c9a66

Battery Value

The battery value contains the latest measurement of the battery voltage. The parameter is a read only float. This characteristic is identified by its unique 128-bit ID. This is: a970fd37-a0e8-11e6-bdf4-0800200c9a66

System Zero

The system zero is a floating point value that is stored in non-volatile memory. This value is subtracted from the final value on each measurement. It is stored as a floating point number.

This value should not be used as a live tare (i.e. for each new measurement). It is designed

such that the zero can be applied at the point of installation and stored in non-volatile memory rather than written multiple times per day. There are 100,000 write cycles on the non-volatile memory before it is worn out.

The system zero value will be converted automatically if a unit conversion is made to the module. This will have no effect if the Linearisation Points is zero. This characteristic is identified by its unique 128-bit ID. This is: a970fd38-a0e8-11e6-bdf4-0800200c9a66

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Configuration Pin

The Configuration PIN controls the access to the device. It must be written to as the first action after connecting to the unit. Until it has verified the value of the Configuration PIN it will always read zero then disconnect the link. Attempting to access any parameter prior to entering a valid Configuration PIN will result in disconnection of the link. The Configuration PIN number is a user settable unsigned 32 bit integer. The default value is 0. This characteristic is identified by its unique 128-bit ID. This is: a970fd39-a0e8-11e6-bdf4-0800200c9a66

Model Name

The model name is a factory set parameter that indicates the type of acquisition module that is present. It is a string of characters that identify the module. Currently there is only one. This is formatted as: “B24-SSBX-A” B24 – B24 range SSB - Strain Sensor Bridge X -OEM Module A -Standard Variant

This characteristic is identified by its unique 128-bit ID. This is: a970fd3a-a0e8-11e6-bdf4-0800200c9a66

Firmware Version

The firmware version is a read only parameter. The value is stored as a float and updated when new firmware is generated. This characteristic is identified by its unique 128-bit ID. This is: a970fd3b-a0e8-11e6-bdf4-0800200c9a66

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Telemetry Data Service

The telemetry data service is where the main measurements are exposed. The status and data values may be enabled in notification mode. The characteristics within this profile will be used by all users planning to use the device in a connected mode. This service is identified by its unique 128-bit ID. This is: a9712440-a0e8-11e6-bdf4-0800200c9a66

Status

The status value is an unsigned integer. The format of the data is the same as in the advert. The full details of the values are shown in Table 2. The application can register to receive notifications * from this parameter. This characteristic is identified by its unique 128-bit ID. This is: a9712441-a0e8-11e6-bdf4-0800200c9a66

Data Value

The data value is transmitted as a float in IEEE 754 format. The application can register to receive notifications * from this parameter. This characteristic is identified by its unique 128-bit ID. This is: a9712442-a0e8-11e6-bdf4-0800200c9a66

Data Units

The data units are transmitted as an unsigned integer value. This can be decoded using the lookup table in

Appendix B - Units. The format and value is identical to the broadcast advert.

This characteristic is identified by its unique 128-bit ID. This is: a9712443-a0e8-11e6-bdf4-0800200c9a66

* When registering for notifications from the Status and Data Value characteristics be

aware that the notifications will only occur at the rate of the current Data Rate.

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Telemetry Calibration Service

The telemetry calibration profile is used by advanced users to access the linearization routines and the advanced access to the internal memory. Access to these values is protected by the Calibration PIN.

Note that even in connected mode the measurements are still only being taken at the

Data Rate (Or Fast Rate) so time needs to be given to allow applied inputs to be reflected in the measurements before calculating new gains and offsets.

This service is identified by its unique 128-bit ID. This is: a970fd30-a0e8-11e6-bdf4-0800200c9a66

Sensitivity Range

The full Scale input sensitivity of the module is selectable. There are four sensitivity ranges available and corresponding input sensitivity is given in Table 4.

Sensitivity Parameter

Full Scale Sensitivity

0 (default)

±6 mV/V

±12 mV/V

±24 mV/V

±48 mV/V

Table 4: Sensitivity ranges

If the input exceeds the full scale sensitivity + 20% then the overrange flag will be set in the Status.This characteristic is identified by its unique 128-bit ID. This is: a9717261-a0e8-11e6-bdf4-0800200c9a66

Coefficient (@Index)

The coefficient parameter is used to read or write the linearization points into the unit. The value is stored as a float. The storage method and the values that should be written to each index during calibration are described in the Operation Examples section titled Calibration. This characteristic is identified by its unique 128-bit ID. This is: a9717262-a0e8-11e6-bdf4-0800200c9a66

Linearisation Index

The linearisation index parameter indicates the current location that will be written to by the coefficient parameter. This characteristic is identified by its unique 128-bit ID. This is: a9717263-a0e8-11e6-bdf4-0800200c9a66

Linearisation Repeat

The linearization repeat parameter is used to set the size of the table used during calibration. The value of this parameter is currently set to three which indicates a linear calibration. Higher order calibrations (i.e. quadratics) are advanced and not supported or described here. This characteristic is identified by its unique 128-bit ID. This is: a9717264-a0e8-11e6-bdf4-0800200c9a66

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Linearisation Points

The linearization point’s parameter is used to set the number of calibration points used in the calibration. This characteristic is identified by its unique 128-bit ID. This is: a9717265-a0e8-11e6-bdf4-0800200c9a66

Base Value

The base value is the measurement presented in factory calibrated units (i.e. without user calibration). The value is a read only float. Prior to running the calibration this value will match the Engineering unit value. For the strain module this value is in mV/V terms. This characteristic is identified by its unique 128-bit ID. This is: a9717266-a0e8-11e6-bdf4-0800200c9a66

Base Units

This parameter indicates the units that the factory calibrated the unit in. The base unit will correspond to the measurement type. The Strain module will report the base value in mV/V. This characteristic is identified by its unique 128-bit ID. This is: a9717267-a0e8-11e6-bdf4-0800200c9a66

Data Gain

The data gain value is used when applying a unit conversion to a calibration. An example of how this is applied is in the Operation Examples section titled

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Unit Conversion.

This characteristic is identified by its unique 128-bit ID. This is: a9717268-a0e8-11e6-bdf4-0800200c9a66

Data Offset

The data offset value is used when applying a unit conversion to a calibration. An example of how this is applied is in the Operation Examples section. This characteristic is identified by its unique 128-bit ID. This is: a9717269-a0e8-11e6-bdf4-0800200c9a66

Calibration PIN

The Calibration PIN may be used to protect the calibration of the unit. The connecting app can optionally request a Calibration PIN from the user and access to calibration pages in the app may be restricted if the PINs do not match. The default value is 0. This characteristic is identified by its unique 128-bit ID. This is: a971726a-a0e8-11e6-bdf4-0800200c9a66

Calibration Units

This unit should be written with the units corresponding to the calibration. The value written to this parameter should correspond to the unit look up table found in Appendix B - Units. This characteristic is identified by its unique 128-bit ID. This is: a971726b-a0e8-11e6-bdf4-0800200c9a66

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

Advanced Index

The advanced index is used to access the internal memory of the device. This should not normally be required. The address locations that can be used are given in Appendix C - Advanced Parameters. It is recommended that the Advanced Index be read back after writing to confirm that it has been changed correctly before writing to the Advanced Data characteristic. This characteristic is identified by its unique 128-bit ID. This is: a971726c-a0e8-11e6-bdf4-0800200c9a66

Advanced Data

The advanced data parameter is used to read and write to the internal memory of the device that is not exposed through the other characteristics. This should not normally be required. (N.B the format of the data sent should match the destination selected. Failure to do so may lead to unexpected behavior). The address locations that can be used are given in Appendix C - Advanced Parameters. This characteristic is identified by its unique 128-bit ID. This is: a971726d-a0e8-11e6-bdf4-0800200c9a66

Connection Security

The Mantracourt product uses its own method of securing the link prior to allowing access to the data and calibration. BLE stipulates that the initial connection request must occur without the need for security and this is the case for this product. Once the connection is made any attempt to read data will lead to a disconnect request. This is to avoid vanilla applications halting the delivery of data in the broadcast mode. Furthermore the correct Configuration PIN must be set within 5 seconds of establishing the connection. Otherwise a disconnect command will be issued.

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Operation Examples

This section looks at a few of the common operations that will need to be conducted over Bluetooth and details the methodology involved. This encompasses both the connected and advertising mode of operation.

Decoding Data with View PIN

The encoding applied to the data in the Bluetooth advertising packet is very simple but effective. It works on the principle of a shared ASCII View PIN. Each individual character of the View PIN is used to apply an XOR on the corresponding data. This means that the value delivered is difficult to decipher without knowledge of the View PIN. To decode the transmission the same process of XOR is applied. The data tag is repeated twice in an encoded form at the end of the advert and may be used by applications to check that the decoding has been successful. The advert key is encoded by default with a 10 byte seed. Each byte is used in turn to encode the value that is transmitted.

This Default Seed value is:

0x5C, 0x6F, 0x2F, 0x41, 0x21, 0x7A, 0x26, 0x45, 0x5C, 0x6F

The View PIN is repeated in the encoding table. The example below uses a View PIN of ASCII encoded 8742 (The PIN does not need to be numeric. It is entered as a byte array of ASCII characters. 8742 is chosen over the default of 0000 in this example to show how the PIN is repeated).

The example in Table 5 shows how the encryption array is calculated from the View PIN and the Default Seed. The example uses a measured value of 2.54 kg and a data tag of 1234.

Description

Unencoded Value

Encoding array

Seed PIN ▼ ▼

Encoded Transmission

Length field – fixed at 16

0x10

Advert Type

0xFF

Company ID – Mantracourt ID

0xC3

0x04

Format ID

0x01

Data Tag

0x12

0x34

Status

0x00

0x5C XOR 0x38 = 0x64

0x64

Units – from look up table ‘kg’

0x2D

0x6F XOR 0x37 = 0x58

0x75

Data – MSB first

0x40

0x2F XOR 0x34 = 0x1B

0x5B

2.54  0x40228F5C

0x22

0x41 XOR 0x32 = 0x73

0x51

0x8F

0x21 XOR 0x38 = 0x19

0x96

0x5C

0x7A XOR 0x37 = 0x4D

0x11

Data Tag

0x12

0x26 XOR 0x34 = 0x12

0x00

0x34

0x45 XOR 0x32 = 0x77

0x43

Data Tag

0x12

0x5C XOR 0x38 = 0x64

0x76

0x34

0x6F XOR 0x37 = 0x58

0x6C

Table 5: Example of encoding the advert

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Connection

The device operates in a general discoverable mode. As such the device is always broadcasting its advert at the set interval and is open to connections. A defensive connection mechanism is employed on the device. This involves disconnecting any device that does not enter the correct value into the Configuration PIN within 5 seconds. The process flow is as follows:

 Scan for devices  Select required corresponding device MAC address and connect  Send the Configuration PIN to characteristic a970fd39-a0e8-11e6-bdf4-0800200c9a66 attributed to

service a970fd30-a0e8-11e6-bdf4-0800200c9a66.

 Read required aspects and configure as appropriate.  Disconnect to allow device to resume transmitting advertising packets.

Once connected the app can use the data profile to read data and register for notifications or configure the device and disconnect and use the broadcast adverts.

Reading Data

When reading from the device the data will be returned in the format stored in the device.

Examples:

Reading the Status characteristic (a9712441-a0e8-11e6-bdf4-0800200c9a66) when there are no errors (zero) will return 1 byte as shown below.

0x00

Data Value = 0 as unsigned integer 8 bit

Reading the View PIN characteristic (a970fd34-a0e8-11e6-bdf4-0800200c9a66) to 1234 as shown below. Note full length of string is always returned and unused characters are padded with NULL character.

0x31

0x32

0x33

0x34

0x00

Data Value = 1234 as string

Reading the Configuration PIN characteristic (a970fd39-a0e8-11e6-bdf4-0800200c9a66) of 1234 will return 4 bytes as shown below.

0x00

0x04

0xD2

Data Value = 1234

as unsigned integer 32 bit

Reading the Data Value characteristic in engineering units (a9712442-a0e8-11e6-bdf4-0800200c9a66) when 2.54 mV/V is applied and no calibration will return 4 bytes as shown below.

0x40

0x22

0x8F

0x5C

Data Value = 2.54

as floating point

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Writing Data

When writing to the device the data must be formatted to the native characteristic format defined (See Appendix

A).

Examples:

Writing the View PIN characteristic (a970fd34-a0e8-11e6-bdf4-0800200c9a66) to 1234 as shown below. Note following NULL character.

0x31

0x32

0x33

0x34

0x00

Data Value = 1234 as string

Writing the View PIN characteristic (a970fd34-a0e8-11e6-bdf4-0800200c9a66) to NULL as shown below. Note following NULL character.

0x00

Data Value = NULL as string

Writing the Configuration PIN characteristic (a970fd39-a0e8-11e6-bdf4-0800200c9a66) to 1234 as shown below.

0x00

0x04

0xD2

Data Value = 1234 as unsigned 32 bit

Writing the Data Gain characteristic (a9717268-a0e8-11e6-bdf4-0800200c9a66) to 100 as shown below.

0x42

0xC8

0x00

Data Value = 100 as floating point

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Calibration

The calibration involves setting the gain and offset values in particular regions of operation of the load cell. This can be achieved through table calibration or live calibration.

Procedure

Action

Description

1. Initialisation of parameters

Set the Linearisation Repeat Set the Linearisation Points

Set the Sensitivity Range

Should be 3 (default) Set to one for a two point calibration. Set to required range (default 0  ± 6 mV/V)

2. Take readings – Live Cal

Skip this stage if conducting the table cal.

Apply low input. Receive input from user for the expected Low Data Value in engineering units. Read and store Low Base Value Apply high input. Read and store High Base Value Receive input from user for the expected High Data Value in engineering units.

3. Calculate Gain and Offset

Please see example below.

4. Program coefficients

Set the Calibration Units. Set the Data Units. Set the Data Gain = 1. Set the Data Offset = 0. Set the Linearization Index to 0. Write the linearization table terms (values for each cell in the table. Start from top left progressing through each column then on to the next row by incrementing the Linearisation Index).

The calibration coefficients can be thought of as a table with a number of columns and rows. The number of columns is set by the ‘Linearisation Repeat’ value and the number of rows is set by the ‘Linearisation Points’ value. For a two point calibration the table has three columns and one row. The first column holds the base unit value where the calculation becomes valid. The second column holds the gain and the third column holds the offset. There is an extra row in the first column to indicate where the range ends. This is easier to explain with an example:

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Given a table Cal (or the data gathered from a live calibration where 10 pounds weight corresponds to 2.0 mV/V and the 0.0 pound weight gives 0.2 mV/V. The gain and offset values are:

Gain =

HighDataValue - LowDataValue

HighBaseValue - LowBaseValue

10 - 0.0

2.0 - 0.2 =

5.56 Offset =

Gain x LowBaseValue - LowDataValue

(5.56 x 0.2) – 0.0

1.11

To enter this information into the linearization table the device needs to know the range within which the calculation is valid (this is a little moot on a two point calibration but is required when extending to a multi-point calibration). With the example given above the table becomes:

Valid from (base units i.e. mV/V)

Gain

Offset Valid to (base units)



-6

5.56

1.11

Table 6: Example of linearization table

In this example the range of valid values has been chosen to be the full range of the load cell mV/V input with sensitivity range set to 0 (±6 mV/V). In order to write to this table we first set the number of rows and columns required and set the index to zero. The linearisation values in the table are then written in turn starting from the top left and progressing through each column before proceeding to the next row.

Page 20

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Unit Conversion

The unit facilitates a method of unit conversion between Calibration Units and Data Units by writing Data Gain and Data Offset values into the device.

Following on from the calibration example which was calibrated in pounds, this section will apply a conversion to kilograms.

Procedure

Action

Description

Prepare for conversion

Read the Calibration Units.

Calculate the conversion gain and offset.

See below.

Write the parameters to the unit.

Write the Data Gain Write the Data Offset Write the Data Units

-From calculation below

-Not normally required (use zero).

-from look up table

The conversion is calculated based upon the Ratio values in the Appendix B table. The first step is to divide by the Calibration Units Ratio and then multiply by the required Data Units Ratio.

Display Gain =

Data Units Ratio

Calibration Units Ratio

2.204585538

0.4536

After all the parameter values have been written, subsequent transmissions will have been converted to the new unit range. This method may be used to convert between any of the units within the same unit group.

N.B The unit conversion values are held in non-volatile memory and will persist following a power cycle.

System Zero

The system zero may be applied at any point of the commissioning process following the calibration. The value entered into the device incorporates any display unit conversion applied. In order to enable a simpler interface the value read out of the device will be converted to the current Data Units value. The value written into the system zero parameter is subtracted from any subsequent transmission.

To apply a zero to the current measurement, simply write the value of the last measurement into the system zero parameter.

Page 21

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendices

Appendix A - Bluetooth UUID Quick Reference

All the Mantracourt services and characteristics have a common 96 bit tail and a variable 32 bit identifier. 00000000-a0e8-11e6-bdf4-0800200c9a66 The following table shows the 32 bit identifier used to replace the 00000000 shown above to produce the full 128-bit UUID.

Description

Type

Format

Min

Max

a970fd30

Configuration Profile

Service

- - -

a970fd31

Data Rate

Characteristic

Uint32

10000

a970fd32

Resolution

Characteristic

Uint8

a970fd33

Battery Threshold

Characteristic

Float

2.3

3.5

a970fd34

View PIN

Characteristic

String

4 bytes

a970fd35

Serial Number

Characteristic

Uint32

Read Only

a970fd36

Data Tag

Characteristic

Uint16

0xFFFF

a970fd37

Battery Value

Characteristic

Float

Read Only

a970fd38

System Zero

Characteristic

Float

-FLT_MAX

FLT_MAX1

a970fd39

Configuration PIN

Characteristic

Uint32

4294967295

a970fd3a

Model Name

Characteristic

String

Read Only

a970fd3b

Firmware Version

Characteristic

Float

Read Only

a9712440

Data Profile

Service

- - -

a9712441

Status

Characteristic

Uint8

Read Only

a9712442

Data Value

Characteristic

Float

Read Only

a9712443

Data Units

Characteristic

Uint8

255

a9717260

Calibration Profile

Service

- - -

a9717261

Sensitivity Range

Characteristic

Uint8

0 3 a9717262

Coefficient (@Index)

Characteristic

Float

-FLT_MAX

FLT_MAX

a9717263

Linearisation Index

Characteristic

Uint8

a9717264

Linearisation Repeat

Characteristic

Uint8

a9717265

Linearisation Points

Characteristic

Uint8

a9717266

Base Value

Characteristic

Float

Read Only

a9717267

Base Units

Characteristic

Uint8

Read Only

a9717268

Data Gain

Characteristic

Float

-FLT_MAX

FLT_MAX

a9717269

Data Offset

Characteristic

Float

-FLT_MAX

FLT_MAX

a971726a

Calibration PIN

Characteristic

Uint32

4294967295

a971726b

Calibration Units

Characteristic

Uint8

255

a971726c

Advanced Index

Characteristic

Uint8

255

a971726d

Advanced Data

Characteristic

Byte Array2

unknown

Uint8 - unsigned integer 8 bits Uint16 - unsigned integer 16 bits Uint32 - unsigned integer 32 bits String - character array with length given by Max in the table Float - float value in IEEE 754 format

FLT_MAX is 3.402823e+38

The format of the advanced data depends on the parameter that the advanced index is pointing to. The data

is transferred as a byte array and the format of the parameter being written to is applied.

Page 22

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendix B - Units

Number

Hex

Value

Group

Unit

Symbol

Ratio

0x00

ratio

mV/V

0x01

angle

radians

rad

0x02

angle

degrees

57.30659026

0x03

angle

circumference

0.159159637

0x04

angle

grade 63.66197711

0x05

angle

minutes

3437.607425

0x06

angle

seconds

“

206264.7982

0x07

angle

revolutions

rev

0.159159637

0x0F

length

meters

0x10

length

angstrom

10000000000#

0x11

length

astronomical unit

6.69E-12

0x12

length

centimeters

100

0x13

length

chains gunters

0.0497097

0x14

length

ell

0.874890639

0x15

length

236.2391

0x16

length

fathoms

0.546805453

0x17

length

feet

3.280839895

0x18

length

furlongs

fur

4.97E-03

0x19

length

inches

39.37007874

0x1A

length

kilometers

0.001

0x1B

length

league

lea

2.07E-04

0x1C

length

leagues

league

0.00018

0x1D

length

light years

1.06E-16

0x1E

length

lines

472.4424

0x1F

length

microns

1000000

0x20

length

miles nautical

mi n

5.40E-04

0x21

length

miles

6.22E-04

0x22

length

millimeters

1000

0x23

length

mils

mil

39370.07874

0x24

length

nanometers

1000000000

0x25

length

parsec

3.24E-17

0x26

length

yards

1.093613298

0x2D

mass

kilograms

0x2E

mass

drams

dr av

564.3977876

0x2F

mass

grains

15432.7514

0x30

mass

grams

1000

Page 23

Mantracourt Electronics Limited B24 Telemetry Technical Manual

0x31

mass

milligrams

1000000

0x32

mass

ounces

35.27395713

0x33

mass

pennyweights

pwt

643.0165191

0x34

mass

pounds

2.204585538

0x35

mass

kilopounds

klb

2.204585538

0x36

mass

scruples

s ap

771.63757

0x37

mass

slug

6.85E-02

0x38

mass

tons long

ton

9.84E-04

0x39

mass

tons metric

0.001

0x3A

mass

tonnes

tonne

0.001

0x3B

mass

tons short

sh tn

1.10E-03

0x41

force

newtons

9.80665

0x42

force

kilonewtons

0.00980665

0x43

force

millinewtons

9806.65

0x44

force

meganewtons

9.80665E-06

0x45

force

crinals

crinal

0x46

force

dynes

dyn

1000000

0x47

force

grams force

1000

0x48

force

joules per cm

J/cm

0.01

0x49

force

kilograms force

kgf

0x4A

force

kilograms force kp

0x4B

force

kilograms meter/second²

kg ms²

0x4C

force

ounces force

ozf

35.27396195

0x4D

force

pounds force

lbf

2.204622622

0x4E

force

poundals

pdl

70.93163528

0x4F

force

tons force long

tonfl

9.84E-04

0x50

force

tons force short

tonfs

0.001102311

0x51

force

tons force metric

tonfm

0.001

0x5F

pressure

bar

0x60

pressure

atmosphere techn

1.019716213

0x61

pressure

atmosphere phys

atm

0.986923267

0x62

pressure

dyne/cm²

dyncm²

1000000

0x63

pressure

foot of water (39°F)

ftH2O

33.45525633

100

0x64

pressure

inch of water (39°F)

inH2O

401.463076

101

0x65

pressure

gigapascal

GPa

0.0001

102

0x66

pressure

hectopascal

hPa

1000

103

0x67

pressure

kg force / cm²

kgfcm²

1.019716213

104

0x68

pressure

kg force / m²

kgf/m²

10197.16213

105

0x69

pressure

microbar

µbar

1000000

106

0x6A

pressure

pascal

100000

107

0x6B

pressure

newton/m²

N/m²

100000

Page 24

Mantracourt Electronics Limited B24 Telemetry Technical Manual

108

0x6C

pressure

ounce(avdp)/square inch

oz/in²

3215070

109

0x6D

pressure

pounds per square foot

lb/ft²

2088.54

110

0x6E

pressure

pounds per square inch

psi

14.50377439

111

0x6F

pressure

tonne per square cm

T/cm²

0.001019716

120

0x78

speed

meter/sec

m/s

121

0x79

speed

centimeters/sec

cm/s

100

122

0x7A

speed

feet/min

ft/min

196.8503937

123

0x7B

speed

feet/sec

ft/s

3.280839895

124

0x7C

speed

kilometers/hr

km/h

3.599712023

125

0x7D

speed

kilometers/min

km/min

0.06

126

0x7E

speed

kilometers/sec

km/s

0.001

127

0x7F

speed

knots

1.942430403

128

0x80

speed

meters/hr

m/h

3600

129

0x81

speed

meters/min

m/min

130

0x82

speed

miles/hr

mph

2.237136465

131

0x83

speed

miles/min

mpm

3.73E-02

132

0x84

speed

miles/sec

mps

0.000621

133

0x85

speed

nautical miles/hr

n mph

1.943846

134

0x86

speed

nautical miles/min

n mpm

0.0324

135

0x87

speed

nautical miles/sec

n mps

0.00054

150

0x96

torque

newton meter

N m

151

0x97

torque

meter kilogram

m kg

0.101971621

152

0x98

torque

foot pound

ft lbf

0.737562149277266

153

0x99

torque

foot poundal

ft pdl

23.7303604042319

154

0x9A

torque

inch pound

in lbf

8.85074579132716

200

0xC8

arbitrary

counts

255

0xFF

Undefined

Page 25

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendix C - Advanced Parameters

Index

Access

Format

Min

Max

Parameter

Read

FLOAT

0 0 Peak Value – Peak Value since last power up.

Read

FLOAT

0 0 Trough Value – Trough value since last power up

Read and Write

FLOAT

-FLT_MAX

+FLT_MAX

Display Min – Min Value in display units. Causes an overrange flag to be set in status.

Read and Write

FLOAT

-FLT_MAX

+FLT_MAX

Display Max – Max Value in display units. Causes an overrange flag to be set in status.

Read and Write

FLOAT

-FLT_MAX

+FLT_MAX

Filter Level – See Appendix D - Filter

Read and Write

UINT32

4294967295

Filter Steps – See Appendix D - Filter

Read and Write

UINT8

0 1 Linearisation Direction – Set the linearization direction as positive or negative. Default is positive

Action

NONE

0 0 Calculate Coefficients – recalculate the live coefficients. (Is automatically applied at the end of a calibration routine)

Read and Write

UINT32

0 1 Digital Output Function – Set the digital output to follow the LED with a 1.

Read and Write

UINT8

0 0 Fast Mode – determines how the device can dynamically switch between the standard Data Rate and the Fast Rate (Below). 0 = Fast Rate disabled. 1 = On connection. Fast Mode entered when device is connected. 2 = On Level. Fast Mode activated when the measured value exceeds the Fast Level. 3 = On Change. Fast Mode entered when the rate of change between two readings exceeds that calculated as the Fast Level over the Data Rate.

Read and Write

UINT32

0 0 Fast Rate – this is the fast transmission rate entered in milliseconds and is equivalent to the Data Rate. Range is 80 to 10000 milliseconds.

Read and Write

UINT32

0 0 Fast Duration – This sets how long the Fast Mode will be sustained. This is stated in multiples of the Fast Rate. Example. If

Fast Rate is set to 100 (0.1S) and Fast Duration set to 200 then the device will

remain in Fast Mode for 0.1 x 200 = 20 seconds.

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Mantracourt Electronics Limited B24 Telemetry Technical Manual

Read and Write

FLOAT

0 0 Fast Level – This value is entered in Data Units and will be used depending on the Fast Mode as follows: When Fast Mode = 1: The Fast Rate will return to the Data Rate after the Fast Duration period expires from when the device is disconnected. When Fast Mode = 2: this value when

exceeded triggers Fast Rate returning back to Data Rate when the level drops below this value and after the Fast Duration period has elapsed.

When Fast Mode = 3: this level sets the

rate of change level which triggers Fast Rate returning back to Data Rate when

the rate of change drops below this value and after the Fast Duration period has elapsed.

189

Action

NONE

0 0 Restart module.

192

Action

NONE

0 0 Shunt Cal On – Apply 100 k Shunt Cal.

193

Action

NONE

0 0 Shunt Cal Off – Remove Shunt Cal

194

Action

NONE

0 0 Tare – Apply a local tare to the measurement (N.B does not persist through power up)

195

Action

NONE

0 0 Reset Tare – Reset Tare value to zero.

196

Action

NONE

0 0 Reset Peak and Trough

197

Action

NONE

0 0 Restore EEPROM Defaults – Restore all default values. (Calibration would be lost. Factory Cal remains.)

Page 27

Mantracourt Electronics Limited B24 Telemetry Technical Manual

Appendix D – Filter

The filter level and filter steps affect the frequency response of the input which is indicated at the bottom of the page.

The Dynamic filter is basically a recursive filter and therefore behaves like an electronic ‘RC’ circuit. It has two user

settings, a level set in the calibrated engineering units and the maximum number of steps (up to 255).

This filter is very basic and operates at the mV/V level.

Instead of outputting every new value, a fraction of the difference between the new input value and the current filtered value is added to the current filtered value to produce the filtering action.

If this difference is less than the value set in the Filter Level then the fractional amount added each time is decremented until it reaches the minimum level set by Filter Steps i.e. Filter Steps is the limit of the divisor.

e.g. if Filter Steps = 10 the fractional part of the difference between the new value and the current filtered value will be added to the current filtered value.

If a rapidly changing or step input occurs and the difference between the new input value and the current filtered value is greater than the value set in Filter Level then the output of the filter will be made equal to the new input reading i.e. the fractional amount of the new reading added to the current reading is reset to 1. This allows the Filter to respond rapidly to fast moving input signals.

When a step change occurs which does not exceed Filter Level, the new filtered value is calculated as follows:

New Filter Output value = Current Filter Output Value + ((Input Value - Current Filter Output Value) / Filter Steps)

The time taken to reach 63% of a step change input (which is less than Filter Level) is dependent on the frequency at which values are passed to the dynamic filter, set in Data Rate, multiplied by Filter Steps.

The table below gives an indication of the response to a step input which is less than Filter Level.

% Of Final Value

Time To settle

63%

Data Rate * Filter Steps

99%

Data Rate * Filter Steps * 5

99.9%

Data Rate * Filter Steps * 7

For example, If Data Rate is set to 10Hz = 0.1s and Filter Steps is set to 10 then the time taken to reach a % of step change value is as follows.

% Of Final Value

Time To settle

63%

0.1 x 10 = 1 seconds

99%

0.1 x 10 x 5 = 5 seconds

99.9%

0.1 x 10 x 7 = 7 seconds

Page 28

Mantracourt Electronics Limited B24 Telemetry Technical Manual

The following table shows the number of updates ‘x Filter Steps’ and the ‘% Error’ that the Filtered Output value will differ from the constant Input Value.

x Filter Steps

% Error

36.78794412

13.53352832

4.97870684

1.83156389

0.67379470

0.24787522

0.09118820

0.03354626

0.01234098

0.00453999

x Filter Steps

% Error

0.00167017

0.00061442

0.00022603

0.00008315

0.00003059

0.00001125

0.00000414

0.00000152

0.00000056

0.00000021

Remember: if the step change in mV/V is greater than the value set in Filter Level then: New Filter Output value = New Input Value i.e. the output jumps to the new input value and the internal working value of Filter Steps is reset to 1. This is then incremented each update (set by Measurement Rate) until it reaches the user set value of Filter Steps.

The filter can be disabled by entering zero for Filter Steps.

Document Title:

B24 Telemetry Technical Manual

Applies To:

B24 Product Range

Part Number:

517-944

Issue Number:

02.01

Dated:

14th March 2019

In the interests of continued product development, Mantracourt Electronics Limited reserves the right to alter product specifications without prior notice.

www.mantracourt.com

Mantracourt B24, B24-SSBX-A Technical Manual

Specifications and Main Features

Frequently Asked Questions

User Manual