PWS-400 User`s Manual - Prairie Wind Systems
Contents
1. The 11 bit character is sent least significant bit first left to right as shown with 1 start bit 8 data bits a parity bit and one stop bit The default parity of the device is even parity Odd parity and no parity are also supported When no parity is specified 2 stop bits should be used so that the 11 bit character size is maintained 1 2 3 4 5 6 7 8 9 10 11 Start Bit O Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Stop Stop 8 1 2 RTU Message Format An RTU message is comprised of a sequence of 4 to 256 characters transmitted in a continuous stream No more than 1 5 character times should be permitted between the characters in a message The format of a message is as follows Slave Address Function Code Data CRC 1 byte 1 byte 0 to 252 bytes 2 bytes 31 PWS 400 User s Manual By default for baud rates less than or equal to 19200 an idle time of 3 5 character times signifies the end of a message For baud rates higher than 19200 an idle time of 1 75 milliseconds signifies the end of a message The RTU mode uses a Cyclical Redundancy Check CRC to provide error checking across a message from the slave address to the last data byte Only the eight data bits of each character are used in generating the CRC start and stop bits and the parity bit do not apply The CRC field is a 16 bit value The low order byte is appended first followed by the high2. 3 4 5 6 7 8 9 10 Start Bit O Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Stop Stop Although not specified by the MODBUS standard the PWS 400 will also support the ASCII mode using 8 bit characters with or without parity as described for the RTU mode 32 PWS 400 User s Manual 8 2 2 ASCII Message Format An ASCII message is comprised of a sequence of 9 to 513 characters The format of a message is as follows Start Slave Address Function Code Data LRC End 1 char 2 chars 2 chars O to 504 chars 2 chars 2 chars CR LF 1 byte 1 byte 0 to 254 bytes The ASCII colon character begins a message The message ends with the ASCII control characters carriage return CR and line feed LF The byte information of an ASCII message from the slave address to the end of the data is identical to that of an RTU message Each byte of the message is transmitted as two ASCII hexadecimal characters 0 9 A F By default intervals up to one second may elapse between characters within the message The device supports a programmable timeout interval up to 60 seconds Intervals exceeding the timeout value will cause the device to assume an error has occurred and discard the message Each reception of a colon character signals the beginning of a new message If a message was in the process of being received when a colon is recei
3. IL LI II M Prairie Wind I Systems LLC PWS 400 MODBUS Data Module User s Manual 14 10400 10 20 2013 PWS 400 User s Manual Copyright 2012 2013 by Prairie Wind Systems LLC All Rights Reserved No part of this document may be photocopied reproduced or translated to another language without the prior written consent of Prairie Wind Systems The information contained in this document is subject to change without notice Prairie Wind Systems has made a reasonable effort to ensure that the information contained in this document is accurate as of the date of publication Prairie Wind Systems makes no warranty of any kind with regards to this material including but not limited to its fitness for a particular application Prairie Wind Systems will not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material In no event shall Prairie Wind Systems be liable for any claim for direct incidental or consequential damages arising out of or in connection with the sale manufacture delivery or use of any product PWS 400 User s Manual 1 MO PS DO Regulatory Informations eege Eeer EES 5 1 1 SREL 5 1 2 Battery Statement siisii aa aE a vaxecten DEE REESEN EEN ebe RENE 5 Warranty and Assistance nan than Atari lat Eia eie AbT E EAEra teni e 6 OVE OW a RAR AR aiment seta tease Eeer 7 Ke LSC d E 8 l
4. device 13 PWS 400 User s Manual 7 Register Map The PWS 400 uses the MODBUS Holding Registers data model exclusively All of the device functionality is accessed using the MODBUS read and write holding register commands The organization of the register map is kept consistent among Prairie Wind System devices as much as practical 7 1 Device Configuration Registers The device configuration registers identify the device its site location and its basic configuration Device Configuration Registers Register Size Data Default Number Registers Type Access Name Value 1000 1 USHORT R Register Map Version 2 1001 1 USHORT R Device Id 400 1002 2 ULONG R Serial Number 1004 1 USHORT R Firmware Version 1005 1 USHORT R Boot Code Version 1006 1 USHORT R Hardware Version 1007 1 USHORT R W Site Id 0 1008 16 STRING R W Site Name 0 1024 32 USHORT R W Site Information 0 1056 1 USHORT R W Device Address 1 1057 1 USHORT R W Low Voltage Warning Threshold 9600 mV 7 1 1 Register Map Version This is the version of the register map supported by the device This provides for the modification of the register map at a future date and detection of the difference by the master device 7 1 2 Device Id This is the model number of the device It can be used to validate the system configuration and to identify the available feature set 7 1 3 Serial Number This is the serial number of
5. following table Device Status Register Bit Mask Name Description 0 0x0001 Power Outage A power outage caused a hardware reset and recovery 1 0x0002 Low Voltage The input voltage is below the warning threshold 2 0x0004 Clock Battery Timekeeping backup battery is low 3 0x0008 Clock Fault Timekeeping restarted at 2000 01 01 00 00 00 00 4 0x0010 Clock Adjusted Date and Time were changed 5 0x0020 Device Fault A device fault caused a reset and recovery 6 0x0040 Temperature Device operating temperature range was exceeded 7 0x0080 Reserved Always returns 0 8 0x0100 Encryption Enabled Encryption key is non zero data records will be encrypted 9 0x0200 Reserved Always returns 0 10 0x0400 Reserved Always returns 0 11 0x0800 Reserved Always returns 0 12 0x1000 Reserved Always returns 0 13 0x2000 Reserved Always returns 0 14 0x4000 Reserved Always returns 0 15 0x8000 Reserved Always returns 0 The status register is non volatile information is retained across a power outage The status represents events that occurred since the last time the register was cleared The device status is recorded with each logged data record The status register can be cleared at any time by writing zero to it Any conditions that persist or reoccur after being cleared will cause those bits to be set again Attempting to 17 PWS 400 User s Manual write any value other than zero to clear t
6. of messages received that were rejected with an exception response 20 PWS 400 User s Manual 7 5 Data Log Recording Registers These registers configure data log security and allow the master device to record registers in the data log Data Log Recording Registers Register Size Data Default Number Registers Type Access Name Value 1300 8 STRING W Encryption Key 1320 1 USHORT W Register Count 1321 64 USHORT W Data Registers 7 5 1 Encryption Key Write this 8 register string to set a 128 bit encryption key Afterwards all data records written to the data log will be encrypted using this key The registers are write only so that the key is protected The registers are non volatile so the key need only be written once prior to recording data When shipped from the factory or after a factory defaults command is issued the key is erased and encryption is disabled Issuing a factory defaults command does not remove encryption from data already stored in the data log It is recommended that the user not mix data recorded with different encryption keys or mix encrypted and unencrypted data in the same log as this will make decrypting the log difficult Changing the encryption key does not change the encryption of previously recorded data The data log should be erased prior to or immediately after changing the encryption key Note It is the responsibility of the user to manage encryption keys
7. order byte The high order byte of the CRC is the last byte in the message A slave device will not act on or respond to a message that has an invalid CRC or parity errors The master device must discard a slave response with an invalid CRC or parity errors and either resend the message or generate an error Techniques for calculating the CRC can be found in the document MODBUS over Serial Line Specification and Implementation Guide V1 02 available at modbus ida org 8 2 ASCII Transmission Mode In the MODBUS ASCII transmission mode each 8 bit byte in a message is sent as two hexadecimal ASCII characters The message is also framed with unique ASCII characters This mode is preferred when the communication link cannot guarantee the inter character timing required by the RTU mode such as a packet based wireless link 8 2 1 ASCII Character Format The standard format for each character in an RTU message is as follows 1 2 3 4 5 6 7 8 9 10 Start Bit O Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Parity Stop The 10 bit character is sent least significant bit first left to right as shown with 1 start bit 7 data bits a parity bit and one stop bit The default parity of the device is even parity odd parity and no parity are also supported When no parity is specified 2 stop bits should be used so that the 10 bit character size is maintained 1 2
8. password that matches the Security Password will temporarily take the device out of the security mode Logging in with a password that does not match the security password will result in an exception response with the ILLEGAL WRITE VALUE exception code and if the device is in the security mode the device will remain in the security mode Note When password security is in effect the login password is required independently from the RS485 network master device and the Bluetooth master device 28 PWS 400 User s Manual 7 8 Diagnostic Registers These registers provide device diagnostic and troubleshooting information Device Description Register Size Data Default Number Registers Type Access Name Value 9000 1 USHORT R Configuration Flash Writes lt 50 000 9001 1 USHORT R Last Reset Type 0 9002 1 USHORT R Fault Count 0 9003 1 USHORT R Last Fault Type 0 9004 1 USHORT R Last Fault Information 0 9005 1 SHORT R High Temperature C x 10 9006 1 SHORT R Low Temperature C x 10 9007 1 USHORT R Data Log Chip Id 8214 or 9538 9008 1 USHORT R Data Log Erasure Count lt 50 000 7 8 1 Configuration Flash Writes This non volatile register records the number of times the device configuration registers have been written to Since these registers are intended for occasional configuration of the device a high number indicates frequent changes and possibly improper use of the re
9. registers in each record The capacity is calculated as follows 1 Determine R the number of data registers in each record This is the value that is written to the Register Count 2 The number of bytes in a record is B 2 x R 30 3 If encryption is enabled set E B 6 If E is not evenly divisible by 16 increase E so that E is an even multiple of 16 Then set B E 6 4 The number of records in a block is the integer part of N 65532 B A block is the smallest part of the log memory that can be erased when the log begins to wrap around 5 The total number of records is 64 N The calculation assumes that all records will be of equal size For example if 4 registers are written per record R 4 With no encryption the number of bytes in a record is B 2 x 4 30 38 The number of records in a block is the integer part of N 65532 38 1 724 The total number of records is 1 724 x 64 110 336 Once the log becomes full the oldest 1 724 data records will be erased to make room for new data The total number of records can be used to determine how long it will take to fill the log memory at a given recording interval Continuing with the previous example if the recording interval is 5 minutes it will take 383 days to fill the log memory 110 366 x 5 minutes 1440 minutes per day The total number of records can also be used to determine the fastest recording interval that can be used to fill the log memory in a give
10. time clock when power is not applied The Department of Transportation requires that the outside of each package that contains primary lithium batteries regardless of the size or number of batteries be labeled with the following statement PRIMARY LITHIUM BATTERIES FORBIDDEN FOR TRANSPORT ABOARD PASSENGER AIRCRAFT The labeling requirement covers shipping via highway rail vessel or cargo only aircraft and covers all shipments into or out of the United States The label must be in contrasting color and the letters must be 12 mm 0 5 in in height for packages weighing more than 30 Kg and 6 mm 0 25 in in height for packages weighing less than 30 Kg The lithium battery does not contain enough lithium to qualify as a reactive hazardous waste The battery is safe for disposal in the normal municipal waste stream PWS 400 User s Manual 2 Warranty and Assistance The PWS 400 is warranted by Prairie Wind Systems LLC to be free from defects in materials and workmanship under normal use and service for twelve 12 months from the date of shipment unless specified otherwise Prairie Wind Systems obligation under this warranty is limited to repairing or replacing at Prairie Wind Systems option defective products The customer shall assume all costs of removing reinstalling and shipping defective products to Prairie Wind Systems Prairie Wind Systems will return such products by surface carrier prepaid This warranty shall not apply
11. to any product which has been subjected to modification misuse neglect accidents of nature or shipping damage This warranty is in lieu of all other warranties expressed or implied including warranties of merchantability or fitness for a particular purpose Prairie Wind Systems is not liable for special indirect incidental or consequential damages Products may not be returned without prior authorization To obtain a Returned Materials Authorization RMA number contact Prairie Winds Systems at the phone number below Please write the RMA number clearly on the outside of the shipping container Prairie Wind Systems shipping address is Prairie Wind Systems LLC RMAH Z O O Y 7784 Big Sky Court Windsor CO 80550 support prairiewindsystems com Phone 970 460 6066 Fax 970 692 2434 PWS 400 User s Manual 3 Overview The PWS 400 is a MODBUS slave device that adds data logging capability to the master device of a MODBUS RS485 network Standard write and read register commands are used to store and recall data in non volatile memory Data records are free format and are automatically time stamped and check summed Data records can be encrypted for maximum data security When the memory is full recording automatically wraps around to record the newest data over the oldest data In addition to the primary data logging feature the PWS 400 extends the capabilities of a system with these additional features e Data can be
12. 17 7 3 1 Device TC 17 7 3 2 Ambient Temperature eanne onean Eege ne ei See 18 7 3 3 PUL VO TE 18 7 3 4 Charge Voltage meemiin eeaeee ea Eee a eA ae E Ea EEEE EEEE 18 7 3 5 Date and Ni EE 18 7 4 RS485 Configuration Reglsterz ses 19 7 4 1 RS485 Communication SEttiINGS csessssssssssssssssssssssnseseeeseseeeseeeeeseeeeeaeseaeseseaeseaeaeaneeaes 19 7 4 2 RS485 Message Timeout ce cececeeeesnceeceeeeeeeeeeaaeaeceeeeeseesaaaeaeeeeeeeeeesaaaeceeeeeeneeeaaeaeeeeeeeeeeaeas 20 7 4 3 RS485 Sleep TIMEOUT nn ae a a erae eE aa DE E AEE EE ADEREN 20 7 4 4 RS485 Message Counters seen 20 7 5 Data Log Recording Registers iii 21 7 5 1 Encryption E 21 7 5 2 Recording Data enert ege ee eegen ee 21 7 5 3 Calculating Data Record Capacity nn 22 PWS 400 User s Manual 7 5 4 R cording Sped eege eee EE EE EE dade acts ea 23 7 6 Data Log Retrieval Registers bere ccdesdscedenet aie des seein iaaiiai iaee a Ee RANE ESEE Eaa 24 7 6 1 Data Log SiZ cieren naera aa aE a aE E a EREE Eaa 24 7 6 2 Data Log Used WE 24 7 6 3 Lowest and Highest Record Numbers seen 24 7 6 4 Download geleet 25 7 6 5 RECOrd RT Te 25 7 6 6 ege 25 7 6 7 Record Data nn lee th Red der dosette en Eeer 25 7 6 8 Data D CFYDtION Sn nn edel 25 7 6 9 Data R trieval Procedure 3488 see Eed dee tienne tin dE eeh 26 7 6 10 Data Log Download Command sccccecsesssesscecececeseeseaeaeceescesseseuaeeeeeessessesseaeeeeeesseeeees 26 7 7 Password Security Registers ee i
13. 40 to 80 C 40 to 176 F Power Input Input Voltage 8 to 32 Vdc Transient Protection 250 Watts Peak Sleep Current 20 uA typical at 13 5 Vdc network inactive Idle Current 100 uA typical at 13 5 Vdc network inactive Active Current 10 mA typical at 13 5 Vdc RS485 Transceiver Unit Load 1 8 Termination None Common Mode Range 7 Vdc Transient Protection 250 Watts Peak Protocol Half Duplex MODBUS over Serial Line Transmission Modes RTU ASCII Addressing 1 to 247 plus broadcast Baud Rates 1200 2400 4800 9600 19200 38400 57600 Data Bits 7 8 Parity Odd Even None Stop Bits 1 2 PWS 400 User s Manual Data Storage Memory Type 4 MB non volatile flash Data Record Size 1 to 64 registers 2 to 128 bytes Number of Data Records 131 008 1 register per record no encryption to 25 216 64 registers per record with encryption Recording Rate 1 record per second with no wraparound 1 record per 5 seconds after wraparound Recording Endurance 50 000 wraparound and erase cycles Data Security AES 128 Advanced Encryption Standard Data Retention 10 years General Purpose Registe rs Configuration Registers 32 64 bytes non volatile flash Real Time Clock Resolution 0 01 seconds Accuracy 1 minute per month tempera
14. 5 Ee Greet 37 8 5 1 Report ET ME 37 8 5 2 Read RE 37 8 5 3 Write Multiple Registers inner 39 8 5 4 Write Single ET 40 8 5 5 EXC ptiOn RE le ET 41 PWS 400 User s Manual 1 Regulatory Information The PWS 400 has been tested and approved to be compliant to the following regulatory standards e N61326 1 2006 for immunity in industrial locations CE e N55011 2009 Class A Group 1 for emissions CE e CISPR 11 Ed 5 0 2009 05 Class A Group 1 for emissions e CFR Title 47 FCC Part 15 Class A for emissions Any changes or modifications not expressly approved by the party responsible for compliance could void the user s authority to operate the equipment 1 1 FCC Statement This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with this manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense 1 2 Battery Statement This device contains a poly carbonmonoflouride lithium coin cell battery to preserve the real
15. Once written the encryption key cannot be read out of the device Once data is recorded with encryption it cannot be decrypted without the original key 7 5 2 Recording Data Data is recorded in the data log using the following procedure 1 Write the number of registers to be recorded 1 to 64 to register 1320 Attempting to write a value outside this range will result in an exception response with the ILLEGAL WRITE VALUE exception code 2 Write data registers beginning at register 1321 Only the number of data registers specified by the register count can be written Attempting to write more data registers than specified by the register count will result in an exception response with the ILLEGAL ADDRESS VALUE exception code Asingle Write Multiple Registers function can be used to write the register count and the data registers in one transaction 21 PWS 400 User s Manual 3 When the last data register is written as determined by the register count the device will write the record to the data log along with the time site id device id device serial number device status ambient temperature and input voltage The typical response time to this write is less than 100 milliseconds The maximum response time is 3 seconds The register count and data registers are write only to protect unencrypted data from being read 7 5 3 Calculating Data Record Capacity The data record capacity of the data log varies with the number of data
16. Retrieval registers 7 6 5 Record Number Write this register to specify the data record number to read If the write is successful the remaining registers are filled in with the record data and are ready to be read The average response time is 500 milliseconds seconds The maximum response time is 1000 milliseconds Attempting to write a record number less than the lowest record number or greater than the highest record number will result in an exception response with the ILLEGAL WRITE VALUE exception code If a data record is found to be corrupt the device will return an exception response with the CORRUPT DATA RECORD exception code As much of the data record will be retrieved as possible however the register count and or contents of the record are suspect If the register count returns zero the record could not be retrieved A corrupt record can occur if power fails during the time the data record is being written 7 6 6 Record Size After writing the record number this register provides the size of the record in registers The size includes all registers from the first register of the time stamp to the last data register 7 6 7 Record Data After writing the record number the record data registers can be read All data registers may be read including those beyond the record size This permits the master device to read all of the data record registers with one command regardless of the record size Only the data registers specified by th
17. When this register is written the response will be returned with the previous address All subsequent commands must be sent with the new address The register is non volatile 7 1 11 Low Voltage Warning Threshold If the input voltage to the device is less than or equal to this threshold the low voltage warning status bit is set in the device status register The threshold is set in millivolts and can range from 8000 to 32000 mV 8 to 32 volts Attempting to write a value outside this range will generate an exception response with the ILLEGAL WRITE VALUE exception code 15 PWS 400 User s Manual 7 2 Device Command Register The device command register is used to issue command s to the device The register is isolated from other registers in the register map to help prevent accidental writing Device Command Register Register Size Data Default Number Registers Type Access Name Value 1065 1 USHORT R W Device Command 0 Writing a value shown in the following table will issue the corresponding device command Attempting to write any other value will generate an exception response with the ILLEGAL WRITE VALUE exception code Reading the register always returns zero Device Commands Value Name Description 56573 OxDCFD Factory Defaults Resets device configuration registers to their factory default values The encryption key is erased and encryption is disabled Does not a
18. ce Address BYTE 1 247 1 Function Code 128 0x80 BYTE 128 255 Ox80 OxFF 2 Exception Code BYTE 0 255 OxFF 8 5 5 1 Standard Exception Codes The following exception codes are defined by the MODBUS protocol Exception Code Name Description 1 0x01 ILLEGAL FUNCTION The function code received in the command is not valid for the device 2 0X02 ILLEGAL DATA ADDRESS The register address or the register range received in the command is not valid 3 0x03 ILLEGAL DATA VALUE A value contained in the command is not valid such as a mismatch between the number of registers and the byte count This exception indicates an error in the structure of a command 4 0x04 DEVICE FAILURE An error occurred in the device while attempting to perform the command 41 PWS 400 User s Manual 8 5 5 2 Custom Exception Codes The following exception codes are device specific extensions to the standard codes to help speed command response troubleshooting Exception Code Name Description 128 0x80 READ ONLY REGISTER The command attempted to write data to a read only register 129 0x81 WRITE ONLY REGISTER The command attempted to read data from a write only register 130 0x82 ILLEGAL WRITE VALUE The command attempted to write an illegal or out of bounds value 131 0x83 CORRUPT DATA RECORD The requested data record is corrupted 132 0x84 DOWNLOAD END End of fast da
19. clock adjusted bit in the status register 18 PWS 400 User s Manual 7 4 RS485 Configuration Registers These registers specify the communication configuration of the RS485 port RS485 Configuration Registers Register Size Data Default Number Registers Type Access Name Value 1101 1 USHORT R W RS485 Communication Settings 276 1102 USHORT R W RS485 Message Timeout ms 1103 USHORT R W_ RS485 Sleep Timeout ms 1105 USHORT R W RS485 Bad Message Counter 1 1 1104 1 USHORT R W RS485 Good Message Counter 1 1 Oo Oo oO CO oO 1106 USHORT R W RS485 Exception Response Counter 74 1 RS485 Communication Settings This register sets the communication parameters of the RS485 port The default value is 20 0x14 for RTU mode at 19200 baud 8 bits even parity and 1 stop bit The register is non volatile Register Bits Reserved Mode Stop Parity Data Baud Rate 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 default RTU transmission mode 0 1 ASCII transmission mode 1 0 default 1 stop bit 0 2 stop bits 1 default Even parity 0 0 Odd parity 1 No parity 1 0 7 data bits 0 default 8 data bits 1 1200 baud 0 0 0 0 2400 baud 0 0 0 1 4800 baud 0 0 1 0 9600 baud 0 0 1 1 default 19200 baud 0 1 0 0 38400 baud 0 1 0 1 57600 baud 0 1 1 0 When this register is written
20. days 326 days 64 25 216 8 days 17 days 87 days 262 days 7 5 4 Recording Speed The PWS 400 is capable of recording data as fast as 1 record per second provided that the data log has not wrapped around Once the data log has wrapped around the recording rate drops to 1 record every 5 seconds This is necessary in order to provide time for block erasures when the oldest data is erased If the slower rate is undesirable log data should be retrieved before the data log fills then the data log erased and a new log started 23 PWS 400 User s Manual 7 6 Data Log Retrieval Registers These registers allow a master device to retrieve data records from the data log Data Log Retrieval Registers Register Size Data Default Number Registers Type Access Name Value 1400 2 ULONG R Data Log Size bytes 4 194 304 1402 2 ULONG R Data Log Used bytes 0 1404 2 ULONG R Lowest Record Number 0 1406 2 ULONG R Highest Record Number 0 1408 1 USHORT R W Download Record Count 0 1409 2 ULONG R W Record Number 0 1411 1 USHORT R Record Size in Registers 0 1412 4 TIME R Date and Time 0 1416 1 USHORT R Site Id 0 1417 1 USHORT R Device Id 0 1418 2 ULONG R Device Serial Number 0 1420 1 USHORT R Device Status 0 1421 1 SHORT R Ambient Temperature C x 10 1422 1 USHORT R Input Voltage mV 1423 1 USHORT R Register Count 0 1424 64 USHORT R Data Registers 0 1488 4 USHORT R Encr
21. e Registers function code Command Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 6 0x06 2 Register Address USHORT 0 65535 OxFFFF 4 Register Data USHORT 0 65535 OxFFFF Response Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 6 0x06 2 Register Address USHORT 0 65535 OxFFFF 4 Register Data USHORT 0 65535 OxFFFF The register address is one less than the register number e An attempt to write a single register within a multiple register data type will result in an exception response with the ILLEGAL DATA ADDRESS exception code e Some registers are designated as read only R versus R W in the register map Attempting to write data to a read only register will result in an exception response with the READ ONLY REGISTER exception code e Ifan attempt is made to write an out of range value to a register an exception response with the ILLEGAL WRITE VALUE exception code will be returned 40 PWS 400 User s Manual The response to a write single register command is typically returned in less than 100 milliseconds 8 5 5 Exception Response When the device encounters an error condition in a command from the Master it will reply to the command with the standard MODBUS exception response Exception Response Byte Offset Field Description Type Value 0 Devi
22. e register count will contain valid information If the data is unencrypted the register numbers and sizes shown in the table above can be read to extract portions of the data record if not all of the information is needed If the data is encrypted reading individual registers from the table will not be useful A read registers command must be used to read the number of registers specified by the record size All of the registers in the record are required in the decryption process 7 6 8 Data Decryption The Prairie View Software that comes with the device provides data decryption and the capability to view and export data from encrypted logs 25 PWS 400 User s Manual The Advanced Encryption Standard is supported by many operating systems so it is possible for user applications and third party software to decrypt logs providing that the original encryption key is known 7 6 9 Data Retrieval Procedure The following procedure describes data retrieval using conventional MODBUS register read and write commands 1 The master device reads the lowest and highest record number registers to determine the valid record number range and selects the range of records to be downloaded 2 The master device writes a record number to the record number register The PWS 400 retrieves the record from the data log 3 The master device reads the record size register to determine the number of registers in the record 4 The master device
23. ef gr BE 10 5 1 Environmental ConsiderationS iissssssssisaseniateninnnianannieaiiniennreeiiseenir ensti lines 10 5 2 MOUNTING th Devic 55 528 tie nee ae lise en EE en state estate nne tte tetes cet ne de 10 5 3 Connector PIN OUE serres sen nine ie nn pese ni nes ERC Ea EK tien 11 5 3 1 Power R QUiIreM NtS 2 55 eege ee EE ENEE Egger 11 5 3 2 Reger e eege 12 5 4 Terminal BlOCK ACCESSONY ne ne en ee lan adessBeesesdeae e 12 EECHELEN 13 6 1 Devic ConfigUratiOn sise sense en ner eege e 13 6 2 Network Communication Settings sise 13 6 3 Site Identification ar A ee ee eee rev in ne ee 13 El EE 14 7 1 Device Configuration R gist rs 5 ssnlies nie serein nn EEEE A NES EAE nn deeg 14 7 1 1 Register Map WE Ee EE 14 7 1 2 DEVICE Id ne ee th ne A A is etes end essences tie 14 7 1 3 S rial NUMBER ss seen ns ind nitrate 14 7 1 4 lu EIN EE 14 7 1 5 Boot Code Verion areira instant infinie en en et retenue 14 7 1 6 Hardware Version sir Eege Eege tisse legende st qe de 15 7 1 7 ECHT RE 15 7 1 8 Site NAM Gives ES SE EE PE RE 15 7 1 9 Site INFORMATION secs 2022 ne RSR A Ne AR NM EN 15 KO fol We ee 15 7 1 11 Low Voltage Warning Threshold nike inniinn eetet 15 7 2 Device Command Register soeieto niese renren ke aeaa time oaar A Eae Eae eGR EEKE Ta 16 7 3 Device Status Registers ssssssssesssssssssrssrssrstrssnnensstettnsnnessstetensnnesrstensnsansarsttasnsanssteetnsnnansetntt
24. eneee reee min ee EEEE EAEE Eege adele 28 7 7 1 Se Date EE Te essere Re A PNR Et net Peine necsn eee ce ne nenee ed te nette 28 7 7 2 Login PASSWOrd E 28 7 8 Did BNOStic Registers 4 en rene ns queen seen nn dt entente ue eo vie eue te tete nn 29 7 8 1 Configuration Flash Writes iesene eesi ienaa ete nee ates ceed 29 7 8 2 Last Reset TV na re rt ne eege eds entr eee 29 7 8 3 Fault Information anne in ne ie Ne Re NN RER 30 7 8 4 High and Low Temperatures nn side iii nee ei eee ately 30 7 8 5 Data Log CRIN WEE 30 7 8 6 Data Log Erasure COURTE en ARTE ESN AER ed EE AEAEE RERAN 30 MODBUS Protocol cose intranet ess et de deeg iets 31 8 1 RTU Transmission MOde ss instants fins faste ed rs tin et rest tu e nel 31 8 1 1 RTU Character Format ss te te Eege eege ge 31 8 1 2 RTU Message Format ei ekedkERNEECRENERENESAAE CENTRE EEN autre ed EAR EES AEN 31 8 2 ASCII Transmission MOd i sin distri rene ti a rien es 32 8 2 1 ASCII Character Format ssis este ere nes nee es ere enr etat 32 8 2 2 ASCII Message Formats need ions Ee een annees conde 33 8 3 RS EE ER 8 4 BE LES WK 34 8 4 1 USHORT Unsigned Short 34 8 4 2 SHORT Signed KT 34 8 4 3 ULONG Unsigned Long 256468 matanieane fe miam aaaea Aa aae Ee E SEEE eai 34 8 4 4 LONG Signed Long nn ege ee 34 8 4 5 FLOAT Floating Bop css 2ccecccszcectesorisesidecec sade eege e Aee ee 35 8 4 6 STRING Character String amenant inner 35 8 4 7 TIME Date and TiImMe 21 2 22e naine disent Eege 36 8
25. erial Number ULONG 13 Firmware Version USHORT 15 Boot Code Version USHORT 17 Hardware Version USHORT 19 Register Map Version USHORT The response to a slave id command is typically returned in less than 50 milliseconds 8 5 2 Read Registers This function code is used to read the contents of a contiguous block of registers Command Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 3 0x03 2 3 Starting Register Address USHORT 0 65535 OxFFFF 4 5 Number of Registers N USHORT 1 125 0x007D 6 CRC Low BYTE 7 CRC High BYTE 37 PWS 400 User s Manual Response Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 3 0x03 2 Byte Count BYTE 2xN 3 Register Data 2 x N BYTES The starting register address is one less than the starting register number The byte count returned will be two times the number of registers read e If the Read Registers function code is used to read data from a single register the single register must be a single register data type such as a USHORT An attempt to read a single register from within a multiple register data type will result in an exception response with the ILLEGAL DATA ADDRESS exception code e If the Read Registers function code is used to read a multiple register data type the start register address must be of the first reg
26. f time allowed to elapse with no network activity before the device enters its low power sleep mode The valid range for the timeout is 0 or 1000 to 60000 milliseconds 1 to 60 seconds A value of zero disables the low power sleep mode The register is non volatile After the device enters its sleep mode any activity detected on the network will cause the device to wake however the contents of the first message will most likely be missed If this first message was a command addressed to the device the master device will receive no response and must retry the command Afterwards as long as there is network activity more frequent than the sleep timeout setting the device will remain awake and process commands Note The sleep timeout takes precedence over the message timeout If the sleep timeout is used non zero it should be set greater than or equal to the message timeout 74 4 RS485 Message Counters The message counter registers provide diagnostic information for troubleshooting communication problems Each counter is reset by writing it to zero The counters roll back to zero after the maximum count value of 65535 is reached The registers are volatile and will reset to zero if power is removed The Good Message Counter counts properly formatted messages that are addressed to the device The Bad Message Counter tracks the number of improperly formatted messages such as those with a bad CRC The Exception Response Counter counts the number
27. ffect the communication settings the data log or the diagnostic registers 56557 OxDCED Erase Data Log Erases the data log Data cannot be recovered after issuing this command The response message is sent after erasure is complete Typical response time is 30 seconds The maximum response time is 90 seconds Erasing the data log does not affect the current encryption key 56541 OxDCDD Download Data Log Starts the fast data download process The maximum response time to this command is 1000 milliseconds Refer to the Data Retrieval Registers section for a description of the command 56320 0xDCO0 Security Mode Places the device in the security mode requiring a master device to log in with a password to regain access The command has no effect if password security is disabled 16 PWS 400 User s Manual 7 3 Device Status Registers The device status registers allow the master device to obtain the current operating status of the device Device Status Registers Register Size Data Default Number Registers Type Access Name Value 1070 1 USHORT R W Device Status 0 1071 SHORT Ambient Temperature C x 10 1072 1 USHORT Input Voltage mV 1073 1 USHORT Charge Voltage 0 mV 1074 4 TIME R W Date and Time UTC 7 3 1 Device Status This register contains device operational status Each bit in the register represents a status value as defined in the
28. gisters 7 8 2 Last Reset Type This register records information about the last reset event that caused the power outage bit to be set in the device status register Reset Types Type Description 0 None recorded 1 Power outage detected by the CPU power lost and restored 2 Brownout detected by CPU marginal power source e g very low battery 3 Brownout detected by the timekeeping circuit marginal power source 29 PWS 400 User s Manual 7 8 3 Fault Information These registers record information about the last fault event that caused the device fault bit to be set in the device status register The fault count records the number of fault events An occasional fault may indicate a normal recovery from an unusual power loss sequence or transient event Frequent faults may indicate hardware damage or a firmware defect Fault Types Type Description None recorded D Invalid interrupt last fault information register updated with interrupt number 5 Memory access violation 6 Watchdog timeout 7 8 4 High and Low Temperatures These registers record the ambient temperature extremes in degrees Celsius multiplied by 10 experienced by the device 7 8 5 Data Log Chip Id This register reports the identification of the internal data log chip The value may be any one of the values listed in the table 7 8 6 Data Log Erasure Count This non volatile register reco
29. he pin out follows the MODBUS specification for RS485 connections using this style of connector Pin Name Description 1 GROUND Signal and power supply common 2 POWER Positive power input 8 to 32 Vdc 3 MODE No connection 4 A No connection 5 RS485B RS485 transceiver positive terminal 6 D No connection 7 C No connection 8 B No connection 9 RS485A RS485 transceiver negative terminal For reliability of the connection the mating connector should utilize the mounting standoffs provided The cable length should be kept as short as practical The maximum length of cable for an RS485 network is 4000 feet 1200 meters 5 3 1 Power Requirements The wide input voltage range of the device permits operation on a 12 volt or 24 volt DC supply The device will automatically shut down if the input voltage falls below 7 volts and will not resume normal operation until the input voltage rises above 8 volts Sustained operation above 32 volts will damage the device The input is reverse polarity and transient protected Apply the positive side of the supply to pin 2 POWER the negative side to pin 1 GROUND 11 PWS 400 User s Manual 5 3 2 RS485 Signals Pin 5 of the connector is the positive transceiver signal RS485B Pin 9 is the negative transceiver signal RS485A No signal termination resistance is provided internally In most low power applications no additional termination resist
30. he register will generate an exception response with the ILLEGAL WRITE VALUE exception code 7 3 2 Ambient Temperature This register returns the ambient temperature in degrees Celsius C multiplied by 10 providing a temperature resolution of 0 1 C For example an ambient temperature of 23 7 C will be read as 237 7 3 3 Input Voltage This register returns the input voltage applied to the device in millivolts mV For example an input voltage of 13 54 volts will be read as 13540 7 3 4 Charge Voltage This register returns the charging voltage applied to the device in millivolts mV The PWS 400 does not support battery charging and will always return zero 7 3 5 Date and Time These registers hold the current date and time as a TIME data type The device is programmed to Universal Coordinated Time UTC at the factory and generally does not need to be adjusted If the clock should require adjustment it is recommended that UTC continue to be used as the clock does not provide for automatic adjustments for local Daylight Savings Time The time stamps of stored data may be post processed to any local time as needed for reporting or analysis When setting the clock the year must be in the range 2000 to 2399 Leap years in this range are correctly handled Attempting to write an invalid date or time will generate an exception response with the ILLEGAL WRITE VALUE exception code Setting the clock will clear the clock fault bit and set the
31. ignificant temporal digit first ranging from 1000 years to 0 01 seconds Only BCD digits 0 to 9 are used Time is in the 24 hour format Register Byte 1 Byte 2 1000 years 100 years 10 years Year Register 1 Byte 1 Byte 2 10 Months Month 10 Days Day Register 2 Byte 1 Byte 2 10 Hours Hour 10 Minutes Minutes Register 3 Byte 1 Byte 2 10 Seconds Seconds 0 1 Seconds 0 01 Seconds 36 PWS 400 User s Manual 8 5 Function Codes The MODBUS Protocol defines a variety of standard function codes for reading and writing data to a device Only the function codes described in this section are supported by the device All other function codes will generate an exception response with the ILLEGAL FUNCTION exception code 8 5 1 Report Slave Id This function code is used to read the device description All of the device specific information is also available in the register map and is detailed in that section Command Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 17 0x11 Response Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 17 0x11 2 Byte Count BYTE 18 3 Slave Id BYTE 80 0x50 P 4 Run Status Indicator BYTE 255 OxFF ON 5 Slave Id Version USHORT 1 7 Device Id USHORT 400 9 S
32. ister in the field and the number of registers must include all registers in the field If one or both parameters are invalid the device will return an exception response with the ILLEGAL DATA ADDRESS exception code e The Read Registers function code can be used to read data from multiple registers of the same or different data types In this case the starting register address must be of either a single register data type or the first register in a multiple register data type The last register read must be either a single register data type or the last register in a multiple register data type Attempting to start or end the read within a multiple register data type will result in an exception response with the ILLEGAL DATA ADDRESS exception code e Some registers are designated as write only W versus R W in the register map Attempting to read a write only register the device will result in an exception response with the WRITE ONLY REGISTER exception code The response to a read registers command is typically returned in less than 50 milliseconds 38 PWS 400 User s Manual 8 5 3 Write Multiple Registers This function code is used to write the contents of a contiguous block of registers Command Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 16 0x10 2 Starting Register Address USHORT 0 65535 OxFFFF 4 Number of Regi
33. last register in a multiple register data type Attempting to start or end the write within a multiple register data type will result in an exception response with the ILLEGAL DATA ADDRESS exception code e Some registers are designated as read only R versus R W in the register map Attempting to write data to a read only register will result in an exception response with the READ ONLY REGISTER exception code 39 PWS 400 User s Manual e Ifan attempt is made to write an out of range value to a register an exception response with the ILLEGAL WRITE VALUE exception code will be returned e Ifthe function returns an exception response with an exception code of ILLEGAL DATA ADDRESS or READ ONLY REGISTER no data was written to any of the registers e Ifthe function returns an exception response with an exception code of ILLEGAL WRITE VALUE or DEVICE FAILURE data was written to registers up to but not including the register that caused the exception No data was written to registers after the register that caused the exception There is no provision in the exception response to isolate the problem register The response to a write multiple registers command is typically returned in less than 100 milliseconds 8 5 4 Write Single Register This function code is used to write the contents of a single register Only single register data types can be written with this function Writing to a multiple register data type requires the Write Multipl
34. lding Registers model exclusively MODBUS uses big endian representation for register numbers and data items when a numerical quantity larger than a single byte is transmitted the most significant byte is sent first Register data are packed as two bytes per register the first byte contains the high order bits and the second byte contains the low order bits The device extends the big endian representation to data types requiring multiple registers The first register contains the high order bytes and subsequent registers contain the lower order bytes 8 4 1 USHORT Unsigned Short An unsigned short is a 16 bit unsigned integer value in the range 0 to 65535 The value is contained in a single register This is the basic MODBUS holding register data type Register Byte 1 Byte 2 Bits 15 8 Bits 7 0 8 4 2 SHORT Signed Short A signed short is a 16 bit two s complement signed integer value in the range 32768 to 32767 The value is contained in a single register Register Byte 1 Byte 2 Sign Bits 14 8 Bits 7 0 8 4 3 ULONG Unsigned Long An unsigned long is a 32 bit unsigned integer value contained in two consecutive registers Values can range from 0 to 4 294 967 295 Register Register 1 Byte 1 Byte 2 Byte 3 Byte 4 Bits 31 24 Bits 23 16 Bits 15 8 Bits 7 0 8 4 4 LONG Signed Long A signed long is a 32 bit
35. n Configuring the device consists of writing user specific settings to one or more of the device registers The Prairie View Software supplied with the device provides a convenient step by step means to configure the device and is the recommended place to start Refer to the software manual for instructions on installing the software on your desktop computer laptop computer or mobile device It is also possible to configure the device by directly writing to the registers using a master device with pass through capability or using a third party software tool 6 2 Network Communication Settings Before the device is placed on an active RS485 network it must be configured to match the network s communication settings and be assigned a unique device address The device is preconfigured with the MODBUS standard settings of 19200 baud 8 data bits even parity 1 stop bit RTU transmission mode and device address 1 Refer to the Device Configuration section of the device register map to change the device address Refer to the RS485 Configuration Registers section of the device register map if any of the communication settings need to be changed 6 3 Site Identification If the user is collecting data from multiple devices located at different sites it is recommended that the Site Id register be written with a unique value for each site The Site Id is recorded with every data record making it easier to track the data once it has been retrieved from a
36. n time Again using the example above if data will be retrieved once per month a recording interval as fast as 30 seconds can be used 31 days 86 400 seconds per day 110 336 the data log will actually fill in 38 days at this interval The following tables provide some examples of the recording time available for various data record sizes with and without encryption before the log begins to wrap around The tables assume that all data records are the same size 22 PWS 400 User s Manual a Record Recording Interval without Encryption Register Count Capacity 30 seconds 1 minute 5 minutes 15 minutes 1 131 008 45 days 90 days 454 days 1 364 days 2 123 328 42 days 85 days 428 days 1 284 days 4 110 336 38 days 76 days 383 days 1 149 days 8 91 136 31 days 63 days 316 days 949 days 16 67 584 23 days 46 days 234 days 704 days 32 44 608 15 days 30 days 154 days 464 days 48 33 280 11 days 23 days 115 days 346 days 64 26 496 9 days 18 days 92 days 276 days Record Recording Interval with Encryption Register Count 8 Capacity 30 seconds 1 minute 5 minutes 15 minutes 1 110 336 38 days 76 days 383 days 1 149 days 2 110 336 38 days 76 days 383 days 1 149 days 4 110 336 38 days 76 days 383 days 1 149 days 8 77 632 26 days 53 days 269 days 808 days 16 59 904 20 days 41 days 208 days 624 days 32 41 088 14 days 28 days 142 days 428 days 48 31 296 10 days 21 days 108
37. or is necessary If required a resistor may be added externally The maximum offset of the signals from the GROUND at pin 1 is 7 volts Both signals are transient protected 5 4 Terminal Block Accessory The optional PWS 400T Terminal Block accessory board attaches to the 9 pin connector of the PWS 400 and provides terminal block connections for wiring all signals A POWER GND MODE GND ka j t w PWS 68 00405 MADE IN USA HA oO el aa J x z kl D Lu pis POWER C D GND Note Signals A B C D and MODE are not used on the PWS 400 and must be left unconnected 12 PWS 400 User s Manual 6 Getting Started The PWS 400 communicates as a slave device on an RS485 network using the industry standard MODBUS protocol for serial devices This section provides guidelines to getting the device up and running on a network If the device is not already wired follow the installation instructions provided in the previous section Section 7 describes the device register map The PWS 400 uses the MODBUS Holding Registers data model exclusively All of the device functionality is accessed using the MODBUS read and write holding register commands Section 8 provides the details of the MODBUS protocol for users that are not familiar with MODBUS Also refer to Section 8 for device specific implementation information such as the organization of registers into data types 6 1 Device Configuratio
38. rds the number of times the data log has wrapped around and or has been erased 30 PWS 400 User s Manual 8 MODBUS Protocol The PWS 400 utilizes the MODBUS over Serial Line protocol for communication over an RS485 network The MODBUS Serial Line protocol is a half duplex master slave protocol One master device controls the network or link and is connected to one or more slave devices A MODBUS transaction is always initiated by the master device Slave devices never transmit data without first receiving a request from the master device Slave devices never communicate with each other The master device only initiates one MODBUS transaction with one slave device at a time The PWS 400 implements the functions of a slave device in the protocol The MODBUS standard defines two serial transmission modes RTU mode and ASCII mode All devices connected to a network must be configured to use the same transmission mode and communication parameters This device supports both transmission modes 8 1 RTU Transmission Mode The MODBUS RTU Remote Terminal Unit transmission mode is an 8 bit byte oriented binary protocol with timing based message framing The RTU mode is the default transmission mode for the device 8 1 1 RTU Character Format The standard format for each character in an RTU message is as follows 1 2 3 4 5 6 7 8 9 10 11 Start Bit O Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Parity Stop
39. reads the number of registers specified by the size registers beginning with the time register 5 Optionally after the master device has written the record number it can simply read all record registers from the register size through the encryption padding registers and decode the record later 6 The master device repeats steps 2 through 6 until all selected records have been retrieved 7 6 10 Data Log Download Command The following procedure describes the use of the data log download command This command provides considerably faster downloads as compared to conventional register access 1 The master device reads the lowest and highest record number registers to determine the valid record number range 2 The master device writes the first record number to be downloaded to the record number register To download all data set the record number register equal to the lowest record number The PWS 400 has a maximum response time of 1000 milliseconds to this command 3 The master device writes the data log download command to the command register The PWS 400 will return a standard response to this write register command with a maximum response time of 1000 milliseconds 26 PWS 400 User s Manual 4 After a 500 millisecond delay the PWS 400 will begin to stream the number of records specified by the download record count beginning at the record specified by the record number register If the download record count is set to ze
40. recorded and retrieved securely using the Advanced Encryption Standard with a user defined key e The PWS 400 includes an accurate temperature compensated real time clock Every data record logged to the device is date and time stamped The clock is also available to the system master device via simple register reads e The device s ambient temperature sensor is also available via register access In addition to providing temperature compensation for the real time clock the ambient temperature is also logged with every data record for enhanced data tracking and system troubleshooting e The PWS 400 measures and records its system power input voltage This value enhances data tracking and system troubleshooting particularly in battery operated systems The user can track battery and recharging performance in standalone and solar charged systems The Prairie View Software that comes with the device provides a convenient means to configure the device and manage its data log PWS 400 User s Manual 4 Specifications Case Description ABS plastic with integral mounting flanges Dimensions 4 61 L x 2 32 W x 1 30 H 11 7 x 5 9 x 3 3 cm including flanges and connector Weight 3 5 oz 100 g Ratings IP 66 and NEMA 4X Connector 9 pin D sub socket Environmental Operating Temperature 40 to 70 C 40 to 158 F Operating Humidity 5 to 95 RH non condensing Storage Temperature
41. ro the download will continue uninterrupted to the highest record number Each record is constructed as a standard MODBUS read registers response that begins at the record number register and contains all registers in the record There will be little or no delay between records 5 After all records have been sent the PWS 400 will send an exception response with the END DOWNLOAD exception code 6 The master device must be capable of receiving records back to back until it detects the END DOWNLOAD exception The user should consider the following when using this command to download data e There is no handshaking The master device must be capable of receiving records back to back with little or no delay between records Since the record number is included in each record sent and each record contains a CRC or LRC the master device can determine if any records were missed e Onthe RS485 port there is no way to cancel the command The PWS 400 will stream data until it is done The network is unavailable for any other communication until the download is finished e If the PWS 400 encounters a corrupt record during the download it will send an exception response with the CORRUPT DATA RECORD exception code in place of the corrupt record and the download will continue 27 PWS 400 User s Manual 7 7 Password Security Registers Additional module security is available by enabling password protection When a security password is writ
42. sters N USHORT 1 123 0x007B 6 Byte Count BYTE 2xN 7 Register Data 2 x N BYTES Response Byte Offset Field Description Type Value 0 Device Address BYTE 1 247 1 Function Code BYTE 16 0x10 2 Starting Register Address USHORT 0 65535 OxFFFF 4 Number of Registers USHORT N The starting register address is one less than the starting register number The byte count must be two times the number of registers to be written e If the Write Multiple Registers function code is used to write data to a single register the register must be a single register data type such as a USHORT An attempt to write a single register within a multiple register data type will result in an exception response with the ILLEGAL DATA ADDRESS exception code e If the Write Multiple Registers function code is used to write a multiple register data type the start register address must be of the first register in the field and the number of registers must include all registers in the field If one or both parameters are invalid the device will return an exception response with the ILLEGAL DATA ADDRESS exception code e The Write Multiple Registers function code can be used to write data to multiple registers of the same or different data types In this case the starting register address must be of either a single register data type or the first register in a multiple register data type The last register written must be either a single register data type or the
43. ta log download 133 0x85 SECURITY MODE The requested function is not available in security mode 42
44. ten to the PWS 420 the master device must log in with the correct password in order to access any of the device registers When the device is secure only the read slave id function and the write to the login password registers are possible Data Log Retrieval Registers Register Size Data Default Number Registers Type Access Name Value 3000 10 STRING W Security Password 0 3010 10 STRING W Login Password 0 7 7 1 Security Password This ten register non volatile register string sets the password for the device By default the registers are set to zero disabling password protection The device slave id and all device registers are open and accessible Writing a 10 register non zero password to these registers enables password security If no communication port activity is detected after a period of 60 seconds or if the Security Mode device command 56320 is issued the device will enter its secure mode In the security mode only the slave id and the login password registers are available Attempting to perform any other function while in the security mode will result in an exception response with the SECURITY MODE exception code Note It is the responsibility of the user to manage passwords Once written the security password cannot be read out of the device Once the device is secured with a password it cannot be accessed without the original password 7 7 2 Login Password Writing a 10 register
45. the device The master device can read the serial number of the device to provide system traceability 7 1 4 Firmware Version This register identifies the firmware version of the device 7 15 Boot Code Version This register identifies the boot code version of the device The boot code supports field upgrades of the device firmware The boot code on a given device will not change with firmware upgrades Its version is made available to support field upgrade utilities 14 PWS 400 User s Manual 7 1 6 Hardware Version This register contains the hardware version of the device 7 1 7 Siteld The Site Id is a general purpose non volatile read write register The contents of this register are recorded with each logged data record permitting data to be traced to a particular site or system 7 1 8 Site Name The Site Name identifies the site to a user The 16 register non volatile string holds up to 32 characters 7 1 9 Site Information Site Information is comprised of 32 general purpose non volatile read write registers Use these registers to hold system configuration and or calibration data The format of the data contained in the registers is defined by the user They can be used as individual registers or combined to form ULONG FLOAT or STRING data types These registers should not be used to hold data that changes frequently 7 1 10 Device Address The valid range for the device address is 1 to 247 The default value is 1
46. the response will be returned at the previous communication settings All subsequent commands must be sent at the new settings Attempting to write any combination of bits not listed in the above table will result in an exception response with the ILLEGAL WRITE VALUE exception code Note that 7 data bits in the RTU transmission mode is an invalid combination the device will respond with an exception and the ILLEGAL WRITE VALUE exception code 19 PWS 400 User s Manual 7 4 2 RS485 Message Timeout If RTU mode is selected this register specifies the amount of idle time that must elapse before the device recognizes the end of a message A value of zero specifies a timeout that is selected automatically based on the selected baud rate as described in the RTU Message Format section If the master device is unable to meet the default timing requirements a fixed timeout from 5 to 50 milliseconds may be specified The register is non volatile If ASCII mode is selected this register specifies the maximum time that may elapse between characters within a message when the ASCII transmission mode is selected Intervals exceeding the timeout value will cause the device to assume an error has occurred and discard the message The valid range for the timeout in ASCII mode is 1000 to 60000 milliseconds 1 to 60 seconds The recommended setting for most applications is 1000 milliseconds 74 3 RS485 Sleep Timeout This register specifies the amount o
47. ture compensated Backup Battery Life 10 years Temperature Sensor Resolution 0 1 C Accuracy 3 C Voltage Sensor Resolution 0 01 Vdc Accuracy 0 05 Vdc PWS 400 User s Manual 5 Installation 5 1 Environmental Considerations The PWS 400 is specified for operation in a non condensing humidity environment When temperature and or humidity tolerances are exceeded damage to internal components and or measurement inaccuracies due to condensation may result The device must be housed in an enclosure suited for field use The environmental ratings of the device s enclosure are intended as a backup to the primary field housing The field housing should contain desiccant that is replaced or dried frequently enough to control the humidity Effective control of the humidity is the user s responsibility 5 2 Mounting the Device Mounting flanges are integral to the device s enclosure Six mounting holes sized for 4 screws are provided Two or more screws should be used to mount the enclosure gt 461 11 71 M 2 32 5 89 cm 1 80 4 57 cm 4 09 10 39 cm y4 10 PWS 400 User s Manual 5 3 Connector Pin Out The PWS 400 uses a standard 9 pin D subminiature socket The sockets on the face of the connector are numbered as shown below This is also the pin out looking at the wiring side of the mating 9 pin D sub plug 9 8 7 6 The function of each pin is described below T
48. two s complement signed integer value contained in two consecutive registers Values can range from 2147483648 to 2147483647 Register Register 1 Byte 1 Byte 2 Byte 3 Byte 4 Sign Bits 30 24 Bits 23 16 Bits 15 8 Bits 7 0 34 PWS 400 User s Manual 8 4 5 FLOAT Floating Point A float is a 32 bit IEEE 754 floating point value contained in two consecutive registers Register Register 1 Byte 1 Byte 2 Byte 3 Byte 4 SXXXXXXX XMMMMMMM MMMMMMMM MMMMMMMM S is the sign bit X is the 8 bit exponent and M is the 23 bit mantissa 8 4 6 STRING Character String A string is a sequence of consecutive registers where each byte within a register represents an 8 bit ASCll encoded character A string of N characters requires N 2 registers When reading or writing a string all characters in the string must be transmitted If the string to be written does not require the full available length the unused characters must be padded with zeroes Register Byte 1 Byte 2 Character 1 Character 2 Register 1 Byte 1 Byte 2 Character 3 Character 4 Register N 2 1 Byte 1 Byte 2 Character N 1 Character N 35 PWS 400 User s Manual 8 4 7 TIME Date and Time Time is represented by 16 packed BCD digits contained in 4 consecutive registers The registers are organized with the most s
49. ved the previous message will be discarded The ASCII mode uses a Longitudinal Redundancy Check LRC to provide error checking across a message from the slave address to the last data byte The beginning colon and ending CR LF pair are not included in the calculation Only the data bits of each character are used in generating the LRC start and stop bits and the parity bit do not apply The LRC is an 8 bit value encoded with two ASCII characters in the same manner as a data byte A slave device will not act on or respond to a message that has an invalid LRC or parity errors The master device must discard a slave response with an invalid LRC or parity errors and either resend the message or generate an error Techniques for calculating the LRC can be found in the document MODBUS over Serial Line Specification and Implementation Guide V1 02 available at modbus ida org 8 3 Device Addressing The MODBUS master device has no specific address only the slave devices have an address Each slave device on a network must be assigned a unique address Slave addresses can range from 1 to 247 Address 0 is reserved as the broadcast address The device will recognize the broadcast address as well as its own address No response is returned to broadcast requests 33 PWS 400 User s Manual 8 4 Data Types The MODBUS Protocol defines four primary data models Discrete Inputs Coils Input Registers and Holding Registers The PWS 400 uses the Ho
50. yption Padding Registers 7 6 1 Data Log Size This register returns the data log memory size in bytes 7 6 2 Data Log Used This register returns the number of data log memory bytes currently used Combined with the data log size the register can be used to calculate the percent of memory used and percent of memory remaining 7 6 3 Lowest and Highest Record Numbers If no records have been logged both the lowest and highest record numbers will be zero Records are numbered beginning at record one The highest record number will increment with each record logged the highest record number is also the total number of records recorded since the log was last erased As long as the data log hasn t wrapped the lowest record number will remain at one Once the log wraps around the lowest record number will begin to advance as the oldest data is deleted Every record will have a unique and always increasing number If the user keeps track of the last record number that was retrieved only higher record numbers will need to be retrieved at the next download 24 PWS 400 User s Manual 7 6 4 Download Record Count This register specifies the maximum number of records to transfer when the Data Log Download command is used The default value of zero permits continuous streaming of data records This record is non volatile The content of this register has no effect when reading data records via the Data Log
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