Hello.

I have an ET 200SP with a CM PtP (6ES7 137-6AA00-0BA0) that I need to communicate with over Modbus with several third-party modules. I have been looking online for example codes and the only thing I can find is examples where the slave devises are also Siemens.

I have been following this article: https://support.industry.siemens.com/cs/attachments/68202723/68202723_S7-1500_ModbusRTU_DOKU_V1d1_en.pdf

and I am using that sample code that is being described there. It seems very confusing but I think I am getting it somewhat. J I’m not quite sure how I retrieve the data. I have for an example two devise o the same kind that are:

Half duplex

                Must allow up to 500ms for response

                Minimum read-request interval is 100ms or longer

Mudbus ID: 45 and 52

19200 baud rate

                8 data bits

                Even parity

                1 stop bit

                Big-endian, MSB first order

The first data entry in this device starts at 0x2000. The data I need to retrieve is 0x2016 all the way up to 0x202D.

So my questions are:

How do I setup other devises then Siemens in TIA PORTAL, Devises and Networks? (See picture Device & Networks)

Where do I setup the response time and read-request interval?

What do I put in "Comm_Data".Slave[1]."PORT"? (See picture OB100)

Do I use the EN on the Slave block to start retrieving data? (See picture OB1)

Do I retrieve the data from the slaves in the Comm_Data? (See picture Comm_data)

I hope I am somewhat on the right track here and someone can help me.

Best Regards,

Ari

Hello,
The sample combines both Master and Slave functions, where an S7-1500 is the Master, and a ET200SP is playing the role of two slaves devices (simulates 2 RTU). Just to show both aspects of the problem.

But in your situation, I understood that the S7-PLC will be the Master.
You will only need to implement the "master" FB. No slave code in your case.

In the sample, the data block COM_DATA has the COM_DATA.Master_com array you will have as much elements as third party RTUs. The array is made from UDT of type "Data_for_Master".
Such an UDT contains the Job parameter for a slave and also a buffer of 8 Words where the data will be received.
So,  you have to configure as the job details fort each RTU. See 5.2 and 5.3 in the mentionned document.
If you need more space for the data because you read more than 8 words,
change the size of the data in the UDT, and correct COM_DATA.

The third party devices will not appear in TIA at all.

jklm

Hello,
The sample combines both Master and Slave functions, where an S7-1500 is the Master, and a ET200SP is playing the ...

 Hi. I have now been trying everything with no luck. I am running a very simple program. i have a Comm_Loader in an OB100 and one Maser bloc in OB1. I was getting a 818B error that got solve by unchecking the Optimized block access on the DB tha i use for DATA_PTR. that seemed to do the trick i was suddenly getting no errors (7002) and the Tx light was blinking. Then after i tried switching the cables at T/RA- and T/RB+ and turned the PLC back on then the Master block started blinking between 7000 and 8281. Even though I swiched the cables back. (I swiched them to start with because i wasn't shout whether or not it was A to A and B to B or vice versa.)

But now i have found out that if i have the comm_Loader block in the OB1 then I am back to having no errors and the Tx light is blinking.

I am getting very desperate to finding a solution.... 

I put the two versions in to a Dropbox link along whit the Modbus info that came with the slave devise I am trying to connect to. 

If anyone could help me out i would appreciate it a great deal 

Regards Ari

Hello,

Because the Comm_load will take several cycles to execute completely,  you must call it in OB1. But you trigger it only once on its REQ input, till it returns a DONE (or an error that you must evaluate).

Only then you use the Master function to read/write data to the slaves.

RS485 is a bus, so normally you do not cross the wires.

Because you have the LED showing traffic, I am afraid that you request the wrong registers from the devices. The Master function also returns error codes that you must trap with a conditional move (move status to a memory in case of error).

8186 Invalid Modbus station address
8188 Invalid Mode specified for broadcast request
8189 Invalid Data Address value
818A Invalid Data Length value
818B Invalid pointer to the local data source/destination: Size not correct
80C8 Slave timeout. Check baud rate, parity, and wiring of slave

Hello,

I finally got the Modbus up and running. My problem was that I hade to set the wire mode within the Modbus_Comm_Load_DB that is in the System blocks folder. It is default set to 0 meaning that the PtP was set to send out owe RS232. In my case it was supposed to be in mode 4 = half duplex RS485.

Thanks for the help

Hello all,

i have a some problem. Recive give me status : 7002. I can get an answer in the first two queries. When the number of queries 7-8, It leaves to the query. Modbus_Comm_Load returns with DONE. Modbus_Comm_Load Mode : 4. 

I do not know what to do. Please help me.

Hello,

what data types are next registers? Give us Picture of your table of register addresses and data types, as I see your buffer will receive with one request only max. 20 Bytes with LEN defined to 9, is this correct in case of real register address values available?

I would like to read 9 word. 18 bytes required.

I can see the questions and answers. query and answer correctly. but this occurs after the first few attempts. 

He talks about where you will choose the type of data? Is there a choice that way. I thought it was relevant to the choice of the 40001 address.

Hello,

may I understand that you have good communication but first after some attempts? Try connect PC with some MB application to device, this test can show more where can be problem. Give info.