Q&A of common communication problems of Xiamen Yudian thermostat AI artificial intelligence industrial regulator

Q&A for common communication problems of AI artificial intelligence industrial regulator

1. What is the data format of the Yudian AI series instrument?
Answer: 1 start bit, 8 data bits, no parity, 1 or 2 stop bits, baud rate range 4800~19200bit/s;

2. What is the parameter number of the PV value during communication? (Maximum question asked by the customer)
Answer: When the Yudian AIBUS protocol communicates, whether it is reading or writing (whether it is reading/writing any parameter code), the meter will return the PV value, so there is no specific parameter code for PV (measurement value); It can ensure that the PV value can be read at the same time when reading and writing any parameters, so that the system does not affect the refresh rate of the PV value because of the read and write operations on the parameters. When using the MODBUS protocol, due to the limitation of the MODBUS protocol itself, the write data is returned when the parameter is written, and the PV value cannot be returned. Therefore, if the write operation is performed, it is necessary to perform a read operation to read the PV value to maintain the real-time PV. The value update frequency.

3. AI series instruments V8.20 or above are compatible with MODBUS-RTU protocol. What are the specific settings and parameter codes?
Answer: The middle H item of the instrument's internal parameter AF parameter is equal to 1, then AF >= 128; the read length is 4 words, there is no specific one for the PV (measured value) MODBUS address (3.1); for example: read Parameter code 00H (SV value) (ADDR = 1), the data sent is 01 03 00 00 00 04 CRCL CRCH (where 01 is the address, 03 is the read function code, 00 00 is the start address, 00 04 is the read Length, last CRC check); reverse data is MODBUS address 40001 = PV (measured value), 40002 = SV (reference value), 40003 = MV and alarm status, 40004 = value of the parameter read (example = SV value);
(3.2) If the upper limit alarm is read, the starting address is 00 01 (other parameters such as the lower limit alarm is 00 02), then the data is in 40002~40005, 40002 = PV and so on;
(3.3) Regarding the write function, the current write function of AI instrument only supports single write, and does not support batch write (because batch write will take up a lot of communication time, resulting in PV value not being updated in time, affecting the real-time tracking capability of the system), and execution When writing, due to the limitation of the MODUBS protocol, the meter will not return the measured value PV, only return the written data;

4. What is the register name when the AI ​​series instrument communicates with the Kingview or MCGS software?
Answer: Kingview selects Yuguang - AI series instrument - serial port driver. When editing data dictionary, register name has class, class V and class R, class V register read only: V1 is the measured value, V2 is Given value, V3 is the output value MV, V4 is the alarm state; the R class register is defined by the parameter code in the table of the AIBUS communication protocol, and the letter R is added before each hexadecimal code.
The MCGS selects the driver of the Yuguang smart meter; the meaning of the register is the same as the configuration king.

5. About AI multi-channel inspection instrument and AI-7048 communication problem?
A: AI multi-channel inspection instrument and AI-7048 communication are compatible with single-channel instrument in standard mode. For example, AI-706M can be equivalent to 6 AI-501, occupying 6 addresses. The ADDR parameter in the instrument is only set. The starting address of the meter, if set to 1, then the addresses 1, 2, 3, 4, 5, and 6 are occupied by this table. Any table on the bus must not use these addresses, then the next instrument ADDR > 6; AI-702M occupies two paths, AI-704M occupies 4 channels, AI-7048 also occupies 4 channels; in order to speed up communication, the patrol instrument also has a mode of transmitting 3 channel measurement values ​​at a time, see CF parameter selection in the manual. Function, but the communication protocol is not compatible with single-loop instrument in this mode. The PC software needs special processing and few applications, suitable for occasions where large amounts of data need to be collected quickly.

Regulator and single display (V7.0)


Regulator, thermostat and single display (V7.5)

Bit 0

Upper limit alarm (HIAL)

Upper limit alarm (HIAL)


Bit 1

Lower limit alarm (LoAL)

Lower limit alarm (LoAL)


Bit 2

Positive deviation alarm (dHAL)



Bit 3

Negative deviation alarm (dLAL)



Bit 4

Enter overrange alarm (orAL)

Overrange alarm (orAL)


Bit 5

AL1 state, 0 is action


Alternate (0)

Bit 6

AL2 state, 0 is action


0 means MV is the output value, 1 is the status word B.

6. What is the meaning of the AI ​​instrument alarm status?
Answer: The data returned by the meter during communication contains the alarm status, which is the 6th byte in the returned data. The meaning is as follows:

7. Why is there more than one model when the configuration software calls the Yudian OPC server?

A: When you need to add other instrument models, you can install the YDOPC folder under the roller (usually C:\Programfiles\YDOPC) to add the configuration file. Which parameters are needed can refer to the parameter code in the UAI AIBUS communication protocol. The table increases or decreases on its own; unneeded parameters should not be read as much as possible.

8. PLC has integrated MODBUS communication command library. Does U-power's watch support MODBUS communication protocol?

A: At present, the U2000 V8.20 version of the table supports the MODBUS protocol, but some of them do not support the MODBUS protocol. Only the PLC communication port can be used for free protocol communication.

9. When multiple instruments communicate with one PLC, the data will often jump. The most common is Mitsubishi FX series PLC?

Answer: The use of PLC for communication generally uses timed polling. This will happen when the timing is too short. To avoid this problem, the check code of the returned data needs to be compared with the calculated check code.

Namely: PV+SV+ (MV*256+ alarm state) + read/write parameter value + ADDR == check code;

10. The process of doing free port communication with PLC, taking Siemens S7-200 as an example?

A: First initialize the free port, namely: baud rate, data bit, stop bit, parity; initialize the number of received bytes, define the communication timeout time; initialize the global interrupt, initialize the data to be sent, execute the send command (XMT) After the transmission is completed, an interrupt event is generated, a receive command (RCV) is executed, and the receive completion generates a receive interrupt event, and the return data can be processed in the interrupt program; then the next instrument is polled.

11. When does Yudian AI series instrument return data when communicating?

A: Please refer to the following table:

Instrument model

AI-301, AI-7/8 series instruments (V7.X)

AI-5XX series instrument

Latest return time (4800bit/s condition)



Fastest return time (19200 bit/s condition)



Average read and write cycle (under 19200bit/s)



Parameter allows the number of times to rewrite

1 billion times

1 million times

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