Bently Nevada 3500/40M 140734-01 Hot Spare Module

Bently Nevada 3500/40M 140734-01 Hot Spare Module

Connection of transmission interface
3 Software Implementation
The Modbus RTU format communication protocol is used for data transmission in a master-slave manner, where the master station is the active party during the transmission process. That is, the master station sends a data request message to the slave station, and the slave station returns a response message. The data exchange between modbus systems is controlled through function codes. Some function codes operate in place, and the user data for communication is measured in bits:
Status of fc01 read output bit
Fc02 reads the status of the input bit
Fc05 Force Single Output Bit
Fc15 forces multiple output bits
Some function codes operate on 16 bit registers, and the user data for communication is in words:
FC03 Read Output Register
Fc04 Read Input Register
Fc06 Write Single Output Register
Fc16 writes multiple output registers [1]
Communication between CP341 and 3500/92, with CP341 as the master station and 3500/92 as the slave station. Both the master and slave stations need to set baud rates, stop bits, and checksum bits. Here, the baud rate is set to 9600bit/s, with one stop bit and no parity check. The cp341 modbus protocol communication is carried out through simatic step7 programming software and utilizes library functions fb8 (p-snd rk) and fb7 (p-rcv rk) function blocks for sending and reading data operations. They all send source information and receive destination data through the configuration database method. When requesting information, the corresponding fields are read from the source database and sent. The received information is stored based on the content of the sent fields. The message format is stored in the first 6 bytes of db42, and the program is written in statement table language as follows:
L 2
T db42. dbb0//Slave address
L 3
T db42. dbb1//Use fc03 function code
L 5000
T db42. dbw2//The 5000 in base 10 is the starting address of the modbus register configuration area in bently 3500
L 63
T db42. dbw4//63 is the number of 16 bit words to be read from the slave station
Due to the typical response time of the 3500/92modbus rs-232/422 I/O module being less than 0.5 seconds, a data request to the slave station is sent every 0.5 seconds:
An m30.0
When it is 1, issue the read command for an m120.7//
L s5t # 500ms
SD t30//Rate of data requests to bently 3500
A m0.0
R t30
A t30
=M30.0
A m30.0
S m120.7
If a request is being sent, completed or sent incorrectly, the command to read data to the slave cannot be issued:
A m120.7
An db40. dbx 0.0//Send request
An db40. dbx 0.4//Sending completed
An db40. dbx 0.5//Sending error
R m120.7
S db40. dbx 0.0//Send a request command to bently 3500
The sending request must be from the edge:
A（
O db40. dbx 0.4
O db40. dbx 0.5
）
A db40. dbx 0.0
R db40. dbx 0.4
Call the send function block fb8 of cp341:
Call fb8, db50
Sf:=’s’
Req:=db40. dbx 0.0
r: =db40. dbx 0.1
Module address for ladder:=624//cp341
Db_2o:=42//Send data block=db42
Dbd_no:=0//Starting address in db42
Len:=6//6 bytes
R-typ:=’x ‘
Done:=db40. dbx 0.4
Error:=db40. dbx 0.5
Status:=db40. dbw12
Receive slave response data:
Set
=Db41.dbx 0.0//Allow cp341 to receive data
Call fb7, db70
En_r:=db41.dbx 0.0
Ladder:=624
Db_2o:=43//The data block that receives user data
Dbd_no:=0
NDR:=db41.dbx 0.4
Error:=db41.dbx 0.5
Len:=db41.dbw10
Status:=db41.dbw12
3500/92 as a slave only sends data, so the setup is very simple.

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