S7 1214C CPU(Modbus Client), getting 8383 Error

Look at the table from a Modbus slave that shows the register numbers and the corresponding indexed addresses.  Note that register 40001 is address 0000.

Again, I don't know how SIemens CPU's handle addressing, but if Smiffy was right (before this thread got exiled on its own, divorced from the pertinent and relevant previous discussion), then the value 0 at MB_DATA_ADDR should fetch the data that ModSim has at register 40001. 

Hello,

yes, therefore I said if he want use code 03 with holding register and define address on remote system to 2, then his Siemens register value must be logically (40003) - 40001 = 2). Sry I don't know that his SW on PC for simulation of Slave, but from his defined address - 2 is probably clear. Other chaos is that value from SW screen that shows 40002 <15> hehe Sry but I use perfect SW from simplymodbus and don't have any problem.

Hello,

After lot of suggestions, knowledge sharing , may be SPITN got confused or felt Modbus in SIMATIC is very difficult.

My suggestion, don't use Modsim as simulation software. I tried  PLC communication with Modsim but didn't work , always getting same error code 8383. So suggestion would be use either ModScan or Modview as Modbus Simulator software.

If you use same PLC code with other Modbus Server Device or PLC then definitely it will work.

Hello DJ,

<off topic>

sry but here can't be any place for talk about confusions of user, simply he must look to documentations, make tests with approved SWs as simulation, lot of work is waiting for him. Everyone from us had started with some projects, problems... Communication tasks aren't simple.

Hi all,

Thanks for all your suggestions. In india Diwali starts now so after holiday i will test as per your Suggestions then i will let u know. Again Thanks.

Dear all,

  Thanks for your suggestions.

I have used another Simulation software called Modbus View for my TCP client PLC, Now its working well here i am attaching the program for both send & Receive and step by step procedure.(i Think it will be helpful for others)

Software TIA V13 for PLC and MB_Client FB for TCP client (Master)

https://oceancontrols.com.au/datasheet/ocean/ModbusView_TCP_1.61.zip  for  TCP server (Slave). I think this is the best modbus simulation software for siemens PLC. 

PLC Side:

Step-1: Please Enter Correct IP Address of Simulation PC in MB_Client

Step-2: There are 2 MB_Client FB for send and receive with different CONNECT_ID value.

Step-3: Make sure that if any of this FB becomes busy Remove the TRUE of REQ Terminal From That FB.

Step-4: For send/Receive 1 real value MB_DATA_Length  should be 2. (2 words)

PC Side:

Step-1: IP address of PC as MB_Client FB IP address.

Step-2: Select SLAVE and TCP in Configuration setting.

Step-3: Create 2 separate pages for send and receive

step-4: Select Input registers and 40001-4 for send & 40011-14 for receive length should be same as MB_Client.

Step-5: In Status Bar It should show Master connected then Read coils and Write registers.

Hello there, 

This is problem with Modbus Client (MB_Client ) function which sends the query to MB Server Address 255. We usually set this to 1 in our Connect.ID value but for some strange reason, the query is sent to Addr 255. So, a simple solution is just to set the Server ID as 255 on ModSim and this will resolve the issue of Error 8383. 

Apparently, the MB Client DB in System Block -> Program Resources has a Static Tag MB_Unit_ID which is by default initialized to 255. If we change this to 01 and make the connection on ModSim with Server ID as 01 the connection is established. This explains the reason why MB Client polls on 255 ID because it basically wants to know only the IP Address and hence the MB_Unit_ID is set to 255. Some Modbus Server Simulator Softwares ignore this ID and hence they work. ModSim uses both IP Address and Connection ID hence the issue.  

HTH, 

Warmly,

Hrishikesh R

 YES YES YES  . After 2 days of searching and trying every posibiltiy of course there is a modbus unit id that you have to change, but it does not say in any tutorial. 

Thank you again guys. This forum for me is the biggest perks of working with siemens.

HRO26

Hello there, 

This is problem with Modbus Client (MB_Client ) function which sends the query to MB Server Address 255. We usually set this to 1 in our Connect.ID value but for some strange reason, the query is sent to Addr 255. So, a simple solution is just to set the Server ID as 255 on ModSim and this will resolve the issue of Error 8383. 

Apparently, the MB Client DB in System Block -> Program Resources has a Static Tag MB_Unit_ID which is by default initialized to 255. If we change this to 01 and make the connection on ModSim with Server ID as 01 the connection is established. This explains the reason why MB Client polls on 255 ID because it basically wants to know only the IP Address and hence the MB_Unit_ID is set to 255. Some Modbus Server Simulator Softwares ignore this ID and hence they work. ModSim uses both IP Address and Connection ID hence the issue.  

HTH, 

Warmly,

Hrishikesh R