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New Cosmos Electric PS-7-M Communication Specifications Manual

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PS-7-M Communication Specifications Guide
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Carefully read this guide prior to use or maintenance for safe
operation.
Instruction Manual No.
GAE-159-00
June 2020

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Summary of Contents for New Cosmos Electric PS-7-M

  • Page 1 PS-7-M Communication Specifications Guide Keep this guide for easy reference. Carefully read this guide prior to use or maintenance for safe operation. Instruction Manual No. GAE-159-00 June 2020...

  • Page 2: Revision History

    Revision History Revision Document No. Date Contents of change GAE-159-00 June 2020 Initial issue.

  • Page 3: Table Of Contents

    Table of Contents Revision History ............................i Introduction ............................1 1.1 Related Publications ........................2 1.2 Overview .............................3 1.3 Trademark Registration .......................3 1.4 Remarks ............................3 1.5 Symbols Used in this Instruction Manual ..................4 Precautions ............................5 Unit Structure ............................6 Communication Specifications ......................7 4.1 Modbus RTU (RS-485) Communication Specifications ..............8 4.2 Modbus TCP (Ethernet) Communication Specifications .............8 Connection Specifications ........................9 5.1 System Configuration ........................10...
  • Page 4 6.4 Message Examples ........................33 6.4.1 Function Code 03 (Read Single/Multiple Holding Registers) .........33 6.4.2 Function Code 06 (Write Single Holding Register) ............35 6.4.3 Function Code 16 (Write Multiple Holding Registers) .............37 6.4.4 Function Code 23 (Read and Write Multiple Holding Registers) ........39 6.4.5 Exception Response (Response in the event of an error) ..........41 6.5 Register Address Map .......................42 Device Status Information .........................49...

  • Page 5: Introduction

    Introduction Thank you for purchasing the New Cosmos PS-7-M series extractive pump gas detector (hereinafter “detector” or “product”). This detector consists of a main unit and a base unit. A main unit includes a display, a pump and a sensor, while a base unit has external communication terminals to connect to external devices.

  • Page 6: Related Publications

    1.1 Related Publications The following documents have been prepared to guide your installation and use of this product. 1. PS-7-M series gas detector’s instruction manual (Doc.No.GAE-138-xx) This manual provides the following information to ensure safe use of the product.  Safety precautions ...

  • Page 7: Overview

    This guide is intended for administrators/supervisors who perform device setups and data collection from the Modbus master, by connecting the master and the PS-7-M series gas detectors (Modbus slaves) and using the Modbus protocol function codes and their functions.

  • Page 8: Symbols Used In This Instruction Manual

    1.5 Symbols Used in this Instruction Manual Operators’ safety has been put first in designing this product. However, there exist some unavoidable risks due to the system characteristics. In this guide, safety symbols are divided into three categories, Danger, Warning and Caution, depending on the severity and magnitude of the risks.

  • Page 9: Precautions

    Precautions Carefully read the following precautions for correct use. Use this product in accordance with the applicable laws and regulations. Wiring and installation should only be performed by a qualified electrician with knowledge of wiring/installation procedures in accordance with the applicable technical standards. ...

  • Page 10: Unit Structure

    Unit Structure The PS-7-M gas detector consists of a main unit and a base unit. For the details on the main and base units and other parts of the detector, refer to the PS-7-M series gas detector’s instruction manual. Item...

  • Page 11: Communication Specifications

    This chapter describes the communication specifications for this product. Single-master-multiple-slave (SMMS) communication method is used for a system configuration in which Modbus slaves (PS-7-M series gas detectors) can send/receive data to/from the Modbus master. It is assumed that the Modbus master (high-order device) is a personal computer, a programmable logic controller (PLC), or a fieldbus controller in case of Modbus TCP.

  • Page 12: Modbus Rtu (Rs-485) Communication Specifications

    4.1 Modbus RTU (RS-485) Communication Specifications Modbus RTU (RS-485) communication specifications Item Specifications Communication protocol Modbus Communication specifications RS-485 interface Communication method Two-wire half-duplex asynchronous System configuration Single-Master-Multiple-Slave (SMMS) Multi-drop Data format Modbus RTU mode (hexadecimal number (hex code)) Start bit: 1 bit Data length: 8 bits (fixed) (LSB first) Stop bit: 1 bit (fixed) Parity bit: No parity (fixed)

  • Page 13: Connection Specifications

    Connection Specifications This chapter describes the connection specifications for this product. - 9 -...

  • Page 14: System Configuration

    5.1 System Configuration Typical communication system configurations are given below as examples. (1) Typical Modbus RTU (RS-485) configuration Wire multiple slaves in series (multi-drop wiring). Master ＋ － 120 terminal resistor RS-485 (MODBUS RTU) RS - 485 RS - 485 ( ＋...
  • Page 15 Unit ID: 6 Unit ID: N N: 7 to 254 *1. If the switching hub is not PoE-compliant, provide 24 VDC to PS-7-M units. NOTE *2. In case of using a fieldbus controller as a Modbus TCP master. - 11 -...

  • Page 16: Wiring Procedure

    5.2 Wiring Procedure This section explains how to establish a Modbus (RS-485 or Ethernet) network For detailed wiring procedure, refer to the PS-7-M series gas detector’s instruction manual. Turn off the gas detector before wiring to prevent electric shocks.  For precautions to be taken while wiring other than the Modbus terminals wiring, refer to 6.

  • Page 17: Modbus Rtu (Rs-485) Wiring Procedure

    5.2.1 Modbus RTU (RS-485) Wiring Procedure Establish the Modbus RTU (RS-485) communication by taking the following steps. When using the 24 VDC power supply, ensure that the power supply is 24 VDC  10%. Applicable cables: Dia.8–11mm x 2pcs. Use appropriate cables for the installation environment. Terminal resistor 終端抵抗...
  • Page 18 2) Run a power cable thru the grommet (located at the bottom of the base unit), and connect the cable wires to their corresponding power terminals Power terminals Marking Component Function Recommended cable on board Polarity: ＋ Power terminals 2-core CVV cable (Thread size: M3) Power input (24 VDC) Polarity: －...

  • Page 19: Modbus Tcp (Ethernet) Wiring Procedure

    5.2.2 Modbus TCP (Ethernet) Wiring Procedure Establish the Modbus TCP (Ethernet) communication by taking the following steps.  When using the 24 VDC power supply, ensure that the power is 24 VDC 10%.  When using the PoE power supply, ensure that the LAN cable is securely connected. Bottom view of base unit Grommet RJ-4 jack...
  • Page 20  Single-point grounding (grounding at a single point) is mandatory. When the NOTE cable shield from the gas detector is grounded on the power supply side, DO NOT ground the shielded cable to the Earth terminal located inside the gas detector (on the terminal block for power cable) to avoid 2-point grounding.

  • Page 21: Communication Setup

    5.3 Communication Setup This section explains how to set the Modbus (RS-485 or Ethernet) communication.  Set the base unit power switch to the OFF position before using the DIP switches to avoid incorrect operation or device failure.  When the specifications of the connected Modbus master and those of this product do not match, it may cause incorrect operation (e.g.
  • Page 22 The DIP switches are accessible when the address plate is removed. To remove the NOTE address plate, refer to 7-1. “Operation Procedure” of the PS-7-M series gas detector’s instruction manual. - 18 -...
  • Page 23 （ 1 ） Set the IP address type: “DY” or “ST” Select the IP address type between “Dynamic” and “Static” by using the IP address type switch. When “Dynamic” is selected, IP address will be automatically assigned to the detector. The setting here is active when the “ETHERNET (Modbus TCP)”...
  • Page 24 Modbus RTU (RS-485): The address represents the unit ID. Modbus TCP (Ethernet): The address represents the 4th value of the IP address. Refer to the PS-7-M IP address setting guide (separate document) for how to NOTE change the IP address with a web browser.
  • Page 25  If the address is set to “0 (0000 0000)” with the address setting switches, it will NOTE be superseded by the value set by a web browser.  Refer to the PS-7-M IP address setting guide (separate document) for how to change the IP address with a web browser. - 21 -...

  • Page 26: Status Leds

    5.3.2 Status LEDs The status LEDs located on the base unit indicate the LAN cable and communication statuses. Address plate Status LEDs 1 to 3 With address plate removed Component LED No. Description Green When lit, a LAN cable is securely connected to the RJ-45 jack and a Status LEDs switching hub When flashing, Ethernet or RS-485 communication is in progress...

  • Page 27: Communication Protocol

    Communication Protocol This chapter describes the communication protocol. 1. Modbus communication protocol overview 2. Function codes and their functions 3. Response in the event of an error 4. Message examples 5. Register address map - 23 -...

  • Page 28: Modbus Communication Protocol Overview

    6.1 Modbus Communication Protocol Overview Modbus communication uses a single-master-multiple-slave configuration. In Modbus communication, a transaction is always initiated by a master, in which the master sends a request message then a slave returns a response message. 6.1.1 Message Configuration A Modbus message frame consists of the following four items: unit ID (IP address), function code, data and error check code.
  • Page 29 (3) Data This is necessary data for a slave to take action based on the function code. The data configuration differs depending on the function code. It consists of a starting register address, quantity of data, or write data, etc. Data is variable length of up to 125 words (250 bytes).

  • Page 30: Crc-16 Calculation (For Modbus Rtu Only)

    6.1.2 CRC-16 Calculation (for Modbus RTU only) This section describes the CRC-16 calculation method for Modbus RTU (RS-485). CRC-16 generation method (polynomial: X16 ＋ X15 ＋ X2 ＋ 1) 1. Initialize the CRC register (2-byte error check code) to FFFF in hex. 2.
  • Page 31 (4) If there is no match, the slave discards the request message, then waits for a next request message (non-response status). (5) After sending a request message, the master checks if it receives a response from the slave. If there is no response or exception response message (exception code), the master will perform a communication error process.

  • Page 32: Modbus Rtu Communication Interval

    6.1.4 Modbus RTU Communication Interval This section describes the Modbus RTU (RS-485) communication interval Current request Data Start Unit Function Data CRC(L) CRC(H) Data code Idling Idling time(>3.5 time(>3.5 letters) letters) ▲ Previous response message ▲Error check code ▲Current response message Provide a non-communication interval (idling time of more than 3.5-letter) between message frames, to identify the end and start of each message.

  • Page 33: Differences Between Modbus Tcp And Modbus Rtu Protocols

    6.1.5 Differences between Modbus TCP and Modbus RTU Protocols This section describes the differences between Modbus TCP (Ethernet) and Modbus RTU (RS-485) communication protocols. ① Transaction identifier = TRXN ID (data size: 2 bytes) In Modbus TCP communication, the exact value set in the request message (arbitrary) will be included in a response message.

  • Page 34: Function Codes

    6.2 Function Codes The following table lists the function codes supported by this product. Maximum Function code Function data size Remarks Code (words) Read single/multiple - Holding register address 0x03 holding registers range: 40001-49999 Write single holding - Gas concentrations, 0x06 register status information, and...

  • Page 35: Response In The Event Of An Error

    6.3 Response in the Event of an Error This section describes the response in the event of a Modbus communication error. If the slave (this detector) judges that there is an error with a request from the master, the slave will create an exception response message and send it to the master without processing the request.

  • Page 36: Error Codes (Exception Codes)

    6.3.1 Error Codes (Exception Codes) The following table lists error codes (exception codes) supported by this detector. Code Error name Cause 0x01 Illegal function code A received function code is not the one supported by this detector 0x02 Illegal address error - A received Modbus register address is not the one defined by this detector - Writing was performed to a read-only register...

  • Page 37: Message Examples

    6.4 Message Examples This section provides examples of request/response messages per function code supported by this detector, and an example of exception response message in the event of an error. 6.4.1 Function Code 03 (Read Single/Multiple Holding Registers) Function code 03 (0x03) is used to read the data from the specified register addresses. Example of request message The master sends function code 03 (0x03) to the slave (unit ID = 01) in order to read two words of data from register address 41039 (relative address = 1038 (0x040E)).
  • Page 38 Example of response message The slave returns a response message including the “current gas concentration = 25%F.S. (0x0019) and F.S. code = 101 (0x0065)” to the master. Message frame Modbus TCP Modbus RTU Remarks Data item Data Byte Byte size data data (byte)

  • Page 39: Function Code 06 (Write Single Holding Register)

    6.4.2 Function Code 06 (Write Single Holding Register) Function code 06 (0x06) is used to write one word of data to the specified single register. Example of request message The master sends function code = 06 (0x06) to the slave (unit ID = 03). One word (2 bytes) of data for “Host maintenance mode ON command”...
  • Page 40 Example of response message The slave returns a response message (result) informing that “Host maintenance mode ON command” (one word of data) has been written, to the master. Host maintenance mode ON command (with self-resetting) = ON (0x0011) Message frame Modbus TCP Modbus RTU Remarks...

  • Page 41: Function Code 16 (Write Multiple Holding Registers)

    6.4.3 Function Code 16 (Write Multiple Holding Registers) Function code 16 (0x10) is used to write a block of contiguous data to the specified multiple registers. Example of request message The master sends function code = 16 (0x10) to the slave (unit ID = 03). “Test mode ON command” and “test gas concentration”...
  • Page 42 Example of response message The slave returns a response message (result) informing that contiguous data has been written to multiple registers, to the master. Message frame Modbus TCP Modbus RTU Remarks Data item Data Byte Byte size data data (byte) TRXN 0x00 –...

  • Page 43: Function Code 23 (Read And Write Multiple Holding Registers)

    6.4.4 Function Code 23 (Read and Write Multiple Holding Registers) Function code 23 (0x17) is used to perform a combination of one read operation and one write operation. A block of contiguous data will be written to specified multiple registers, then a block of contiguous data will be read from specified multiple registers.
  • Page 44 Message frame Modbus TCP Modbus RTU Remarks Data item Data Byte Byte size data data (byte) Data1 (18) 0x00 – – – Write by the word (19) 0x01 – – Data2 (20) 0x00 – – – (21) 0x19 – – Error –...

  • Page 45: Exception Response (Response In The Event Of An Error)

    6.4.5 Exception Response (Response in the event of an error) When an error (e.g. communication error. Refer to 6.3.1 Error Code for details of errors) occurs, the slave sends an exception response to the master in the following configuration. In an exception response, the slave sets the most-significant bit (MSb) of the function code to “1 (generated by adding 0x80 to the received function code)”...

  • Page 46: Register Address Map

    6.5 Register Address Map This section describes the register address map for the data used by this detector. The detector assigns its data (e.g. gas concentrations, status information, device setup details) to its holding registers. A request message from the master specifies the register addresses to read from/write to. Modbus Register Address Map Relative Register...
  • Page 47 Relative Register Read (R) or Data address Register name Data contents address Write (W) type (hex) 4: %LEL Response example: 0x0001 when code is 1 (ppm). 40013 Sensor unit Mfg. Word Read sensor unit Mfg. No. (8-letter No.(1st and 2nd ASCII code) letters) Response example: When Mfg.
  • Page 48 When X6 = 90%, 0x005A (high-order byte of word data) When Y6 = 90%, 0x005A (low-order byte of word data) 40031 Main unit software Word Read PS-7-M main unit software version version Response example: In case of ver.1.12, 112 = 0x0070 40032 Base unit software...
  • Page 49 Relative Register Read (R) or Data address Register name Data contents address Write (W) type (hex) ON: 0x0011 (with 10-min self-resetting) Host maintenance mode is equivalent to maintenance mode 1, and maintenance mode 2 is prioritized 40051 AL1 set value Word Set AL1 set value Write example: 0x0019 to set to...
  • Page 50 Relative Register Read (R) or Data address Register name Data contents address Write (W) type (hex) b1: Maintenance mode 2 (0:OFF/1:ON) b0: Maintenance mode 1 (0:OFF/1:ON) Response example: When AL1 and AL2 activate while in MNT2, Status byte 1: 0x03 (high-order byte of word data) Status byte 2: 0x02 (low-order byte of word data)
  • Page 51 0x0001: Static IP address 41305 MAC address (1st Word Read MAC address (1st and 2nd bytes) and 2nd bytes) of PS-7-M base unit 41306 MAC address (3rd Word Read MAC address (3rd and 4th bytes) and 4th bytes) of PS-7-M base unit...
  • Page 52 Relative Register Read (R) or Data address Register name Data contents address Write (W) type (hex) 41316 Static IP address Word Set 1st and 2nd values of static IP (high-order) address (high-order) Valid when “0x0001 (static IP)” is set at register address 41304.

  • Page 53: Device Status Information

    Device Status Information This chapter describes the device operation statuses during gas alarm, trouble alarm, test mode, and maintenance mode. - 49 -...

  • Page 54: Gas Alarm Operation

    For gas alarm operation of the main unit, refer to 7-2 “Operation – Gas Alarm” of the NOTE PS-7-M series gas detector’s instruction manual. The device status information (register address: 40516) is one word consisting of two bytes, Status byte 1 (high-order byte) and Status byte 2 (low-order byte).

  • Page 55: Trouble Alarm Operation (Fault Alarm Operation)

    “FLOW” is shown on the LCD and a low flow rate alarm activates (low flow rate 2). For the information on the LCD, refer to 5-6 “LCD Indicator Icons” of the PS-7-M NOTE series gas detector's instruction manual.

  • Page 56: Test Mode Setup And Operation

    “TEST” appears on the LCD of this detector while in the test mode. The test mode will automatically turn off 10 minutes later. To enter the test mode from the main unit, refer to 7-4 “Operation – Test Mode” of the NOTE PS-7-M series gas detector’s instruction manual Registers for test mode setting Register Register name...

  • Page 57: Maintenance Mode Setup And Operation

    For the setup and operation for maintenance modes 1/2, refer to 7-5 “Operation – NOTE Maintenance Mode” of the PS-7-M series gas detector’s instruction manual. The host maintenance mode can be turned on/off from the master by setting the test mode register to on/off via Modbus communication .
  • Page 58  During MNT2, the analog output is fixed at 4.0 mA (or 17.4 mA for oxygen). For the gas alarm contacts and trouble alarm open collector, refer to 7-5 “Operation – NOTE Maintenance Mode” of the PS-7-M series gas detector’s instruction manual. - 54 -...

  • Page 59: Full Scale Codes

    7.5 Full Scale Codes Full scale information is read in a form of 3-digit full scale code (F.S. code). Convert the read F.S. code to the corresponding full scale value by referring to the table blow. Full scale code table F.S.

  • Page 60: Troubleshooting

    Troubleshooting Before requesting repair, please refer to the table below. If the detector does not return to normal operation after performing the corresponding steps in the table, or if your issue is not found in the table, consult New Cosmos or its authorized representative. Symptom Cause Action...
  • Page 61 Symptom Cause Action Reference transmission distance transmission distance are Specifications exceed the specified within the limit. limit.  Check that the RS-485 setting Incorrect conditions 4.1 Modbus RTU of the master and that of this Communication product match, then rewire. Specifications ...
  • Page 62 2-5-4 Mitsuya-naka, Yodogawa-ku, Osaka 532-0036, Japan https://www.newcosmos-global.com...

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