[SM1900B]  RS485 bus protection type temperature sensor

SM1900B SM1900B

Technical Parameters

Technical parameterParameter value
BrandSONBEST
Temperature measuring range-30℃~85℃
Temperature measuring accuracy±0.5℃ @25℃
Communication Interface2 CAN
Default rate250kbps
PowerDC9~24V 1A
Running temperature-30~85℃
Working humidity5%RH~90%RH

Product Size

SM1900B SM1900B SM1900B SM1900B

How to use?

SM1900B

Application solution

SM1900B SM1900B SM1900B

Product List

SM1900B

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SM1900B SM1900B

Communication Protocol

  The product uses the CAN2.0B standard frame format. The standard frame information is 11 bytes, including two parts of information and the first 3 bytes of the data part are the information part. The default node number is 1 when the device leaves the factory, which means The text identification code is ID.10-ID.3 in the CAN standard frame, and the default rate is 50k. If other rates are required, they can be modified according to the communication protocol.
  The device can directly work with various CAN converters or USB acquisition modules. Users can also choose our industrial-grade USB-CAN converters (as shown in the figure above). The basic format and composition of the standard frame are as follows As shown in the table.
76543210
Byte 1FFFTRXXDLC.3DLC.2DLC.1DLC.0
Byte 2ID.10ID.9ID.8ID.7ID.6ID.5ID.4ID.3
Byte 3ID.2ID.1ID.0xxxxx
Byte 4d1.7d1.6d1.5d1.4d1.3d1.2d1.1d1.0
Byte 5d2.7d2.6d2.5d2.4d2.3d2.2d2.1d2.0
Byte 6d3.7d3.6d3.5d3.4d3.3d3.2d3.1d3.0
Byte 7d4.7d4.6d4.5d4.4d4.3d4.2d4.1d4.0
Byte 8d5.7d5.6d5.5d5.4d5.3d5.2d5.1d5.0
Byte 9d6.7d6.6d6.5d6.4d6.3d6.2d6.1d6.0
Byte 10d7.7d7.6d7.5d7.4d7.3d7.2d7.1d7.0
Byte 11d8.7d8.6d8.5d8.4d8.3d8.2d8.1d8.0
  Byte 1 is the frame information. The 7th bit (FF) indicates the frame format, in the extended frame, FF=1; the 6th bit (RTR) indicates the type of the frame, RTR=0 indicates the data frame , RTR=1 means the remote frame; DLC means the actual data length in the data frame. Bytes 2~3 are valid for 11 bits of the message identification code. Bytes 4~11 are the actual data of the data frame, invalid for the remote frame . For example, when the hardware address is 1, as shown in the figure below, the frame ID is 00 00 00 01, and the data can be responded by sending the correct command.
1. Query data
  Example: To query all 2 data of 1# device channel 1, the host computer sends the command: 01 03 00 00 00 02.
Frame type CAN frame ID mapping address function code starting address data length
00 0101010300 0002
    Response frame: 01 03 04 07 3A 0F 7D.
Frame type CAN frame ID mapping address function code data length data
Response frame 00 0001030408 AD 0F 7D
  In the query response of the above example: 0x03 is the command number, 0x4 has 4 data, the first data is 08 AD converted into decimal system: 2221, because the module resolution is 0.01, this The value needs to be divided by 100, that is, the actual value is 22.21 degrees. Each data occupies two bytes, that is, an integer variable. The actual value needs to be divided by 100 on the basis of this value. Similarly, 0F 7D is the second data. Its value is 3965, that is, the true value is 39.65.
2. Change Frame ID
    You can use the master station to reset the node number by command. The node number ranges from 1 to 200. After resetting the node number, you must reset the system. Because the communication is in hexadecimal format, the data in the table Both are in hexadecimal format.
  For example, if the host ID is 00 00 and the sensor address is 00 01, the current node 1 is changed to the 2nd. The communication message for changing the device ID is as follows: 01 06 0B 00 00 02.
Frame type Frame ID Set AddressFunction id fixed value target frame ID
Command 00 0101060B 0000 02
  Return frame after correct setting: 01 06 01 02 61 88. The format is as shown in the table below.
Frame ID Set AddressFunction id source frame ID current frame IDCRC16
00 0001060102 61 88
  The command will not respond correctly. The following is the command and reply message to change the Set Address to 2.
3. Change target frame ID
    You can use the master station to reset the frame ID pointed by the sensor node through the command. The range of the node number is 1~200. After resetting the node number, because the communication is in hexadecimal format, the data in the table is in hexadecimal format.
  For example, if the host ID is 00 05 and the host address that the sensor originally points to is 00 01, the current number 1 will be changed to number 5. The changed communication message is as follows: 01 06 00 6D 00 05.
Frame type CAN frame ID device address function code fixed value target frame ID
Command frame 00 01010600 6D 00 05
  Return frame after correct setting: 01 06 00 01 00 05. Format resolution is shown in the following table.
CAN frame ID device address function code source target frame ID target frame ID check code
00 0001060105 00 00
  If the command is incorrect, it will not respond. Here is the command and reply message to change the device address to 2.
3. Change device rate
    You can use the master station to reset the device rate through commands. The range of the rate number is 1~15. After resetting the node number, the rate will take effect immediately. Because the communication is in hexadecimal format, the rate in the table The numbers are in hexadecimal format.
Rate value actual rate rate value actual rate
120kbps 225kbps
340kbps 450kbps
5100kbps 6125kbps
7200kbps 8250kbps
9400kbps A 500kbps
B800kbpsC1M
D33.33kbps E66.66kbps
  The rate not in the above range is not currently supported. If you have special requirements, you can customize it. For example, the device rate is 250k, and the number is 08 according to the above table. To change the rate to 40k, the number of 40k is 03, the operation communication message is as follows: 01 06 00 67 00 03 78 14, as shown in the figure below.
  After the rate modification is performed, the rate will change immediately, and the device will not return any value. At this time, the CAN acquisition device also needs to switch the corresponding rate to communicate normally.
4. Return frame ID and rate after power-on
    After the device is powered on again, the device will return the corresponding device address and rate information. For example, after the device is powered on, the reported message is as follows: 01 25 01 05 D1 80.
Frame ID device address function code current frame ID current rate CRC16
00 00012500 0105D1 80
  In the response frame, 01 indicates that the current frame ID is 00 01, and the speed rate value 05 indicates that the current rate is 50 kbps, which can be obtained by looking up the table.

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