5S3, MIR & MEC OEM OEM Communications Protocol Manual

Transcription

1 OEM Communications Protocol Manual Analox Limited 15 Ellerbeck Court, Stokesley Business Park, Nort orksire, TS9 5PT, UK UK/RoW T: +44 (0) F: +44 (0) US T: (714) W: E:

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3 List of contents 1 Introduction S3 connections Electrical connections USB connection MIR connections TTL Comms Cable RS485 Comms Cable MEC connection Electrical connections (External) Electrical connections (Internal) Communications settings Sensor node addressing Communications protocol Message format Message cecksum Number formats Messages Document ref: 5S July 2018 Page 0 of 17

4 List of tables Table 1 Electrical Connection... 3 Table 2 Electrical Connections (External)... 5 Table 3 Serial Communications Settings... 7 Table 4 Sensor Specific Details... 7 Table 5 Integer Formatting... 9 Table 6 Sensor Status Flags Table 7 Calibration Control Byte Flags Table 8 Calibration Status Flags Document ref: 5S July 2018 Page 1 of 17

5 1 Introduction Tis document describes te communications protocol to interface wit 5S3, MIR and MEC sensor products. Document ref: 5S July 2018 Page 2 of 17

6 2 5S3 connections 2.1 Electrical connections Electrical connections wit te sensor are made via a sort screened cable. Te cable screen is internally connected to te die cast box and made off into a green/yellow wire. Table 1 Electrical Connection CORE COLOUR SIGNAL DETAILS Red Blue +SUPPL -SUPPL Power Supply 5V DC to Sensor ellow Green + (A) OUTPUT -(B) OUTPUT Signal Output from Sensor (RS485) Green/ellow Eart Screen Use of te screen will depend on te particular installation. It is best connected to a clean Eart to form a sield around te sensor. Note tat it is not recommended for te screen to be connected to te negative supply line. Bonded by te user s fixings, it may not always be desirable to connect te screen to anoter eart connection. If unsure, it is suggested tat te screen wire be connected to eart in te first place and ten if tere are problems, any eart loop can be broken by disconnecting one of te connections in te eart arrangement. Te standard output range is eiter 0 2V or 4 20mA. Maximum load resistance for 4-20mA output is 400Ω. 2.2 USB connection Te 5S3 is fitted wit a USB port to facilitate calibration - calibration software and instructions can be downloaded from te Analox website. Connection to te USB port is not required in normal use. Document ref: 5S July 2018 Page 3 of 17

7 3 MIR connections 3.1 TTL Comms Cable Te TTL Comms cable sould be terminated wit a 6 way Harwin/Molex plug and four connecting wires. Connect as sown below. Te colours are purely for ease of tracing te connections, all te wires will be eiter red or black (Depending if Harwin or Molex connectors). Please twist up te individual wires of te two pairs. +3 to +5V 0V TTL into te sensor TTL out of te sensor 3.2 RS485 Comms Cable Te RS485 Comms cable sould be terminated wit a 6 way Harwin plug (Farnell ) and four connecting wires (Farnell ). Connect as sown below. Te colours are purely for ease of tracing te connections, all te wires will be red. Please twist up te individual wires of te two pairs. +3 to +5V 0V RS485-A (Positive) RS485-B (Negative) Document ref: 5S July 2018 Page 4 of 17

8 4 MEC connection 4.1 Electrical connections (External) Electrical connections wit te sensor are made via a sort screened cable. Te cable screen is made off into a green/yellow wire terminated wit an M4 ring terminal. Tis wire is un-terminated inside te MEC enclosure. Table 2 Electrical Connections (External) TERMINAL CORE COLOUR SIGNAL DETAILS 1 Red +SUPPL Power Supply 5 Blue -SUPPL 4.5 to 5.5V DC 4 Blue RS485 reference Used for 3-wire connection 2 ellow RS485A RS485 communications 3 Green RS485B Use of te screen will depend on te particular installation. It is best connected to a clean Eart to form a sield around te sensor cable. Note tat it is not recommended for te screen to be connected to te negative supply line. Document ref: 5S July 2018 Page 5 of 17

9 4.2 Electrical connections (Internal) Te electrical connections made to te internal electronics are made via clamp terminals. It is important to ensure tat eac core or te cable is connected to te correct terminal. Sown below are te correct electrical connections for te power/comms and Oxygen cell. Document ref: 5S July 2018 Page 6 of 17

10 5 Communications settings To establis communications over te sensor serial bus, te serial connection sould be configured as follows: Table 3 Serial Communications Settings Parameter Value BAUD rate 9600 Data bits 8 Parity None Stop bits 1 Flow control None 5.1 Sensor node addressing All sensors are connected to te same RS485 serial bus and so need to be individually addressed wen communicating. For tis reason, only one sensor can be communicated wit at any one time. A node address value is included in eac message (see section 6.1) to indicate wic sensor is being addressed. Eac sensor will receive te message, but only te sensor wit te matcing node address will reply. Wen replying, te sensor will reply wit its node address in its reply message. For a list of sensor node addresses, see Table 4. Table 4 Sensor Specific Details Sensor type Node address (exadecimal) Output units Carbon dioxide (CO 2) 00 ppm Oxygen (O 2) 40 ppm Carbon monoxide (CO) 50 ppm Volatile organic compounds (VOC) 60 ppm If used individually all sensors can be addressed wit node address ff. Document ref: 5S July 2018 Page 7 of 17

11 6 Communications protocol Tis section gives details of te serial messages tat can be used to communicate wit eac sensor. 6.1 Message format Te standard message format for all communications is as follows: :<NN><M..M><B..B><CCCC><cr> All messages start wit a colon. Eac sensor will look for tis caracter to indicate te start of a message sequence. <NN> - Tis is te node address of te target sensor expressed in exadecimal format (see number formats below). <M..M> - Tis is te command section of te message defining te action to be undertaken by te sensor (see individual message explanations). <B..B> - Tis is te message body and will vary depending on te message type (see individual message descriptions). <CCCC> - Tis is te cecksum value for te message expressed in exadecimal format (see number formats below). <cr> - Te carriage return caracter (0D). A carriage return indicates to te receiving device tat message transmission is complete. 6.2 Message cecksum Te cecksum is te modulo 16 sum of all te caracters between but excluding te colon and te start of te cecksum. Example For te message: :50GV0102<cr> Te cecksum value for te message is te unsigned 16bit value 0102 Te cecksum value is calculated by adding te ASCII caracters 5, 0, G and V. Document ref: 5S July 2018 Page 8 of 17

12 6.3 Number formats All integer values are represented in exadecimal format wit eac exadecimal digit represented by an ASCII caracter (capital for all letters). Values are always represented by pairs of caracters. All bytes are arranged wit most significant byte first. Table 5 Integer Formatting Value size Decimal value Hexadecimal value ASCII representation in message 8 bit 90 5A 5A 16 bit DC 08DC 32 bit EF5DB9 75EF5DB9 Te floating point numbers are encoded in 32 bit IEEEE754 format: Sign bit Exponent Mantissa Te number is given by: 1 sign 2 exp mantissa Note tat te sign bit is te most significant bit of te exponent byte, and te exponent is terefore sifted one bit to te rigt and crosses a byte boundary. In a communications message tey are transmitted as eigt ex ASCII caracters, most significant first. For example, 1.0f would be transmitted as 3F Document ref: 5S July 2018 Page 9 of 17

13 6.4 Messages Poll sensor for gas value Detail: Used to read te current gas value from te sensor Send command: :<NN>GV<CCCC><cr> Reply: :<NN>gv<VVVVVVVV><FFFFFFFF><CCCC><cr> Data: <NN> - (8 bit unsigned integer) Te node address of te sensor <VVVVVVVV> - (32 bit floating point) Te current gas value <FFFFFFFF> - (32 bit unsigned integer) Te sensor status flags (see ) <CCCC> - (16 bit unsigned integer) Te message cecksum <cr> - Te carriage return caracter Notes: Te units of te value returned depend on te sensor type (see ). Te value will be returned as eiter mbar partial pressure or ppm. If ppm output, bit 4 of te status flags will be set (see ). Document ref: 5S July 2018 Page 10 of 17

14 Table 6 Sensor Status Flags Bit Mask Status Notes Warm-up Failed Fault Config CRC error Reference range fault of sensor open circuit Lamp DAC saturated Lamp or PID fault Power supply fault Temperature fault Set at power-up and after eac calibration. Clears automatically after a timeout (20-60 sec). Software as it a fatal error Sensor as identified a fault but is still operating Te sensor as detected a corrupt configuration Sensor lamp reference is out of range (CO 2 only) or cell component is open circuit. DAC for lamp drive as saturated (CO 2 only) PID lamp fault Sensor power supply fault Temperature out of range Noisy Sensor power supply as excessive noise - - Initialisation fault Local pressure Fault Remote pressure Fault Program CRC error Table CRC error User cal points too close Detector / sensor ADC over-range Sensor ADC under-range Over range Under range Sensor did not pass all power-up cecks Te local measured pressure value is out of range Te remote pressure value provided is out of range Te sensor as detected a corruption in program memory Te sensor as detected a corruption in its data tables Te calibration points are too close togeter. Cleared by re-calibrating correctly. Te detection ADC is over maximum usable range Te detection ADC is under minimum usable range Te reading is above te sensor s calibrated range Te reading is below te sensor s calibrated range Document ref: 5S July 2018 Page 11 of 17 Fault * PID power fault Power failure to PID lamp

15 Bit Mask Status Notes PID oscillator fault ppm/mbar output Oscillator fault on PID Tis bit is set if te value returned form te senor is in ppm units. If cleared, te value is returned in mbar partial pressure units AVdd out of 3 AVdd is out of range range *Tis column denotes tat if any of te bits marked are set by te sensor, tey will be accompanied by a set bit 29 wic is te global sensor in fault flag. Fault * Document ref: 5S July 2018 Page 12 of 17

16 6.4.2 Calibrate te sensor Detail: Used to read te current local pressure value from te sensor Send command: :<NN>JG<XX><AAAAAAAA><CCCC><cr> Reply: :<NN>jg<XX><FFFF><CCCC><cr> Data: <NN> - (8 bit unsigned integer) Te node address of te sensor <XX> - (8 bit unsigned integer) Te calibration control byte (see ) <AAAAAAAA> - (32 bit floating point) Te gas value to use for calibration <FFFF> - (16 bit unsigned integer) Te calibration status (see ) <CCCC> - (16 bit unsigned integer) Te message cecksum <cr> - Te carriage return caracter Notes: Wen a calibration message is received, te sensor will determine weter or not a requested calibration adjustment is valid. If te value supplied is determined to be outside of acceptable limits, or would be too large a deviation from te current calibration ten te calibration will be rejected and will not be stored in te sensor s memory. Te calibration status flags indicate te result of te calibration (see ) After eac successfully received calibration command, te sensor will enter a warm-up state wilst te calibration is processed. Te calibration value must be passed as eiter mbar partial pressure or ppm, setting or clearing te appropriate flag bit in te calibration controls byte to indicate wic units type is being provided. Eac sensor s calibration is defined by two calibration points. To fully calibrate a sensor a ig calibration and a low calibration must be performed. Te ig calibration sould generally be performed using a gas concentration towards te ig end of te sensor s range, wilst te low calibration sould be performed close to te low end of te sensor range. In most cases, tis will be zero concentration gas. Te ig or low calibration is performed by setting or clearing te appropriate bit in te calibration control byte (see ). For CO 2 sensors, te concentration of te zero gas sould always contain 0% CO 2. Any oter value passed to te sensor for a low calibration will be rejected. For te CO sensor to calibrate successfully all calibration gases must contain at least a small concentration of O 2 in order for te cemical reaction to take place witin te cell. Te balance gas composition sould reflect te atmospere to be monitored (e.g. use cal. gas wit air balance wen monitoring CO in air). Document ref: 5S July 2018 Page 13 of 17

17 Table 7 Calibration Control Byte Flags Bit Name Description, meaning wen set ppm/mbar Set if calibration value supplied is in ppm units Clear for calibration value in partial pressure units (mbar) Cal point Set for ig calibration, clear for low calibration Table 8 Calibration Status Flags Bit Name Description, meaning wen set Cal Value Hig Cal value too great 6 Cal Value Low Cal value too small 5 Cal Correction Too Big Upper limit of cal correction exceeded 4 Cal Correction Too Small Lower limit of cal correction exceeded Note: If no bits are set ten te calibration adjustment is considered to ave been successfully applied. Document ref: 5S July 2018 Page 14 of 17