Dear All,

as requested by other forum members here aModbus RTU SlaveCommunication function block.

The following SIMATIC S7 communication processor issupported:

• CP340

GENERAL INFORMATION & SUPPORT

For installation, connection and interface configuration of your communication processor module kindly follow its respective documentation.

I also advise you to take some time and go through the general information about Modbus provided by our forum member smiffy. Especially if you are a beginner in Modbus, seek for support or just want to learn more about it.

I hope tomake your life a bit easier with this development.

With Best Regards

TIBI68

SEEKING FOR CP341TO DEVELOP DRIVER FOR CP341

DRIVER DOWNLOAD (ATTACHMENTS)

The attached program files need to be retrieved within the SIMATIC Manager.

Currently there is only one manualfor theCP340version but the others are all working in the same way just with different function blocks.

MBSL340.PDF - Manual for Modbus RTU Master for CP340

MBSL340.ZIP -Example projectfor Modbus RTU Slavedriver for CP340

MANUAL MBSL340

MBSL340

Thanks for downloading !

Some feedback anda click onthe "Thanks" button would be appreciated.

Dear Hopling,

I can make the block for CP341 in no time but I dont have the CP for testing it.

Best Regards.

Dear Hopling,

when it communicates it will work for the full functionality.

Onlythe calls of the standard function blocks will change, the rest of the code will be the same.

I make the changes and will send you the beta to your email for testing.

Gve me some time for that changes while I am a bit busy at the moment.

Best Regards.

Sorry my dearfriend Hoplingbut I am really busy.

For you and other people waitingImodified the block to runwith CP341.

Kindly check it out.

Unfortunate I cannot test it while I dont have that CP here.

Best Regards.

Hello!

Could you add your FB7 and FB8 the project with CP341, because I errors associated with timestamps from the fact that adding blocks FB7 and FB8 of the standard examples. thank you.

P.S. sorry for my poor english.

P.P.S. Today. Try to get a test project for cp341, everything works. Cool. Later, however, there were problems. The main project is a label M101.0 , M101.1 etc. are tied to the core logic . Noticed that FB37 also uses the same tag ( M101.0 , M101.1 , etc.). As a result, there is a conflict and the basic logic is not working properly . Waiting for your help

Hello

I'm trying out the "MBSL341" block in a quite large system with a 317F CPU.

I get the feedback from the block that I'm polling the correct address, use the correct function code, start address, no of registers, but the "Done" flag never goes high.

No error code is indicated by the block either.

Only the RX LED is flashing on the CP, never the TX LED.

I double checked the settings in the HW config.

Can it be that the block is allocating some memories from M100 and upwards ??

These are already used in the PLC program for other purpose (HMI indications), but could be changed if that is the issue.

Bryll

Hello

I'm trying out the "MBSL341" block in a quite large system with a 317F CPU.

I get the feedback from the block that I'm polling the correct address, use the correct function code, start address, no of registers, but the "Done" flag never goes high.

No error code is indicated by the block either.

Only the RX LED is flashing on the CP, never the TX LED.

I double checked the settings in the HW config.

Can it be that the block is allocating some memories from M100 and upwards ??

These are already used in the PLC program for other purpose (HMI indications), but could be changed if that is the issue.

 Hello Bryl,

my blocks do not use any memory bits but maybe the standard blocks do.

Every time you change something at the input parameters of the block or the length of the assigned data blocks for the Modbus address mapping you need to set the INIT bit to TRUE. Otherwise these changes will have no affect and will not be considered.

The best way of an initialization would be through the start-up OB's or in run-time through the online VAT.

Try to make a new initialization, it may fix your problem.

Best of Luck my friend.

It seems that I have something that's bad here.

I'm using the CP341 with an ADAM-4520 RS-422/RS-485 to RS232 converter connected to my laptop.

Everything I send to the CP341 is visible in the code, it even seems to be correct

FB7 and FB8 is also downloaded to the CPU together with the FB37 "MBSL341" block.

RTU slave address is checked and correct, LADDR (1024) of the CP is also correct.

Is it possible that I missed to add any FB or FC to the code, despite the system doesn't warn for anything ?

Next step is to throw the ADAM converter in the trash bin , I suspect that one to be crappy.

Edit:

Replaced the ADAM 4520 converter I used with a brand new one we had in stock, no change.

So I guess the one I use for experimental use can survive a little longer before.

My fault finding will continue.......

The current status is that:

The CP341 reads the data sent to it, the MBSL block shows any change in the data stream such as address, F-code, register start address and no of registers to read.

So far so good.

No reply at all.

I'm using the CP341 RS422/485 in a two wire connection, anyone else that tested this block on such a unit ?

I will now once again go over all the wiring to see if the problem can be found there, but I don't think I will find the problem there.

Perhaps is there a problem in the CP settings.

Hello Bryll,

you can try the following.

1. Reduce the master polls to one only.
2. Open the Instance DB of the MBSL341 Function Block ONLINE and monitor what the block receives.

It would be interesting to see what you get there.

Best Regards.

This is what I get from the CP (attached).

Thanks for the info provided where to find it, had to tweak a bit to open the block.

The settings in Step7 isn't what I'm used to have, new computer and a new installation of the software.

Edit:

Just compared the received data with the sent data from my Modbus tester software. Found a useful one at www.modbus.pl.

I'm asking slave #10 to send 10 coils (F code 0x01) from address 1.

I've tried most everything by now, but the CP is still not sending any reply to the Modbus simulator.

The strange thing is that the message reaches the input buffer and seems to be correct, but the message is not detected to be correct (I guess).

Does the block give an error for anything else than incorrect Modbus commands ?

Is there a fault message anywhere to be found that tells me wrong parity, etc...... anything that can be wrong regarding what ends up in the in buffer.

I used cp341-ICP CON7520 (rs485-rs232 converter) - laptop with the program modbuslook light v1.4. everything works great. the only issue with labels since M100.0, M101.0, M101.1. Label is false or true during the reception and transmission.

g4m3r

I used cp341-ICP CON7520 (rs485-rs232 converter) - laptop with the program modbuslook light v1.4. everything works great. the only issue with labels since M100.0, M101.0, M101.1. Label is false or true during the reception and transmission.

 

 I guess you used the M100.0, M101.0 and M101.1 to initiate and indicate "Done" and "Error".

I used other memories for this and trigger two counters with the "Done" and "Error" tags, nothing is counting so something must be wrong.

I will order another RS232<->RS485 converter since I suspect the one I used is not the best one.

Just got me a Westermo MDW-45, worked a lot with these units earlier.

Connected that one between the CP-341 and my laptop, but no change at all.

The MBSL341 displays everything I send to it, but no response from it.

Am I missing something here ?

I'm using the CP-341-RS422/485 in RS-485 connection, anyone else that got this module working with the MBSL341 FB ?

New CPU, new CP-341 and just a test program with only FB37 (MBSL341) and the required blocks in OB1

CPU 315F (6ES7 315-2FJ14-0AB0

CP341 (6ES7 341-1CH02-0AE0)

The settings for CP341 is exactly as described in the manual.

LADDR was initially 384 for the 341, Process Image wasn't set to OB1 PI until I changed to LADDR 256 in the address tab for CP341.

FB37 is reading and displaying what is sent to it, but it's not sending anything.

So, I changed from two wire (RS-485) to four wire (RS-422) to see if something was changed to the better, but no.

Could you please post what version of the CP341 you have used to get this thing up and running ?

I start to suspect it to be some kind of HW version conflict, but I'm not sure yet.

I'd really like to see it work, since I have the need for a Modbus slave quite often.

I have now tested everything I can.

Last thing was to delete everything and start over with the provided example for the MBSL341.

Changed CPU to what I have, and the CP341 order number to what I have here.

It still doesn't work at all, well it works so I can see what's coming to the CPU.

Since other guys got this block up and running without any problem, am I starting to suspect that there's something that differs between my RS-485/422 unit and their RS-232 units.

I'll be back with a report if I get it up and running with a CP341 RS-232 as soon as I can get hold of one

TIBI68

Sorry my dearfriend Hoplingbut I am really busy.

For you and other people waitingImodified the block to runwith CP341.

Kindly check it out.

Unfortunate I cannot test it while I dont have that CP here.

Best Regards.

Dear TIBI,

I'd love to see what's inside the MBSL341 FB, can you share them without know-how protection?

Kind regards,
Jens

Dear Mr Tibi68

Thank you for your sharing, I just finished testing, Everything works well

kiensnow

Dear Mr Tibi68

Thank you for your sharing, I just finished testing, Everything works well

 Do you use RS232, RS422 or RS485 ?

And what module did you use ?

Trying to find out why it didn't work for me.

Bryll

 I use CP341 RS422/485, firmware version 2.1.6. You should check about your wiring and initial bit.

kiensnow

Dear Mr Tibi68

Thank you for your sharing, I just finished testing, Everything works well

 Do you use RS232, RS422 or RS485 ?

And what module did you use ?

Trying to find out why it didn't work for me.

Hello!

Mr. TIBI68, could you make special version of your library to call SFB58/59 instead of SFB52/53. A have an ancient s7-300, which doesn't support nowadays P_SEND and P_RCV functions.

Best regards,

Dmitry Konstantinov

 Dear,

I have used this block to read 100 holding registers. Initially Data seen on Modscan. But after some time Modscan shown Invalid Response to query and only Rx led glowing on CP340. I have checked all settings in Modscan but I am not sure what is wrong.

Please help....

Hi,

did you tried to restart the Modscan, remove the cable and plug it back or reset the CPU?

If it was working before it would be interesting why it stopped.

Did you made any changes somewhere or was it out of a sudden?

You wrote that Modscan is giving message for invalid response, how is that possible without any Tx LED lit on the CP?

The Modscan has an option to show the actual traffic between the devices.

Maybe you can upload a screenshot.

At the CP the databits should be set to 8 on the interface parameter.

Good Luck!

Do you have any function block for CP341 Modbus slave RS485 protocol RTU?

Thanks man,

Hopling

Hey TIBI, I want to inform you that everything is fine with your MBSL341 FB. I just tested it - working perfect! :D

P.S.

You didn't add FB7 and FB8 in project you attached to last message. FB37 MBSL341 doesn't compiling without it. For me it was not a problem to understand that. But it can be difficult for beginners to find out what's wrong, I guess.

My FB 7, FB8 version is newer than yours so FB37 error when compile. Could you please share your FB7, FB8 with correct version you're using to run FB37

Me too: time stamp is different for FB 7, FB 8 (different version). So FB37 can't run

Please help me to solve this problem.

Dear TIB68,

many times CP340 stops giving data to master.

PLC has to be reset to solve this problem. Is there any solution to avoid PLC reseting. Can i use init bit of block to reset or any other internal reset of blocks (P_SEND_R OR P_RCV_R). The system is 300 R so whenever CPU changeover happens this issue arises.

Thanks in advance for your efforts.

I have no experience with software redundancy.

You might find some help in the documentation about the software redundancy.

Maybe there are some settings you need to take care about when using it together with CP340/CP341.

Sorry that I cannot give you more help.

I am not aware of a reset function for the standard blocks.

Best Regards.

EDIT:

I found an interesting previous post in the following link:

https://support.industry.siemens.com/tf/ww/en/posts/using-cp341-in-s7-300-soft-redundancy/96658?page=0&pageSize=10

There was no solution mentioned how to fix it but maybe you can ask the initiator if he found a solution for this problem in the meantime.

Best Regards.

TIBI68

Hi,

did you tried to restart the Modscan, remove the cable and plug it back or reset the CPU?

If it was working before it would be interesting why it stopped.

Did you made any changes somewhere or was it out of a sudden?

You wrote that Modscan is giving message for invalid response, how is that possible without any Tx LED lit on the CP?

The Modscan has an option to show the actual traffic between the devices.

Maybe you can upload a screenshot.

At the CP the databits should be set to 8 on the interface parameter.

Good Luck!

 HI,

Same Problem I faced. I copied FB7 and FB8 from modbus library MBMA341.

after that It is working fine. superb !!!!!!!

Thanks a lot.

Goodmorning,

Many thanks for the driver provided.

I'm using a s7-300 CPU with CP340 as RS485 for modbus RTU master with step 7.

I'm trying to write a Word (2B) in a single register (modbus function code 6) to a slave (inverter, the only slave of the bus). Once the frame is sent, the slave responds with an error code meaning "invalid data amount", and the FB returns "E57 - CRC checksum error". Seems like more data is sent apart the standard RTU frame.

Right now i'm not able to send you code or actual values of mbma340 istance DB.

I provide the manual of the slave inverter where in page 125 of the PDF there is the message structure in RTU mode.

I see in the send buffer in the istance DB more data than the described message.

I succeded in another application with the same device as slave, but with s7-1200 with CB1241 RS485 with TIA using the functions MB_MASTER and MB_COMM_LOAD.

Many thanks for your help,

Regards

Yes, the instance DB Send & Receive Buffer would help.

Together with the configuration of the MBMAREQ function block.

CRC Error is usually a wiring/configuration mismatch between the mater and the slave (interface parameter).

Also ensure that your Slave is configured for RTU mode.

Best Regards.

TIBI68 

.

Solved!

Hello TIBI68

I have the same problem as Byrll with CP341. Communication is established but only Rx LED flashes and no date is sent from CP341. I need to send Input registers(3xxxx, Function code4) from CP341.  I have updated the firmware version to 2.1.6 but it still does not send any data and used FB7 & FB8 from MBMA340 library. I wonder if the Slave parameter on FB37 should be as the same as output parameter SLADDR(output for received slave address) or not? on my system SLADDR is 60 and I have set slave address both equal to 60 and the default address 1 , no response in both.

I have used an input bit I6.4 from a push button for INIT and press it whenever I make a change in parameter or data block. Is there any problem with this method of initialization?

The attached picture shows other parameters of the block.

I wonder why NREGS(number of regs) and START parameters have such big values and Fcode reads 67 , are they normal?

duongvuquy

Me too: time stamp is different for FB 7, FB 8 (different version). So FB37 can't run

Please help me to solve this problem.

 I am having Same problem. if u have unprotected FB37 kindly share

Ayoob

Hello TIBI68

I have the same problem as Byrll with CP341. Communication is established but only Rx LED flashes and no date is sent from CP341. I need to send Input registers(3xxxx, Function code4) from CP341.  I have updated the firmware version to 2.1.6 but it still does not send any data and used FB7 & FB8 from MBMA340 library. I wonder if the Slave parameter on FB37 should be as the same as output parameter SLADDR(output for received slave address) or not? on my system SLADDR is 60 and I have set slave address both equal to 60 and the default address 1 , no response in both.

I have used an input bit I6.4 from a push button for INIT and press it whenever I make a change in parameter or data block. Is there any problem with this method of initialization?

The attached picture shows other parameters of the block.

I wonder why NREGS(number of regs) and START parameters have such big values and Fcode reads 67 , are they normal?

 hello ayoob

i didn't receive any thing at SLADDER, would you please estimate the problem.

i will be thankful

Hi everybody,

Thanks to TIBI68, I have used this library in my project avoiding paying more money.

Also I took a video to share with more people.

https://www.youtube.com/watch?v=GwsNBwAG7nE

Hi TIBI68,

one quick question about CP340 module's variants:

CP 340–RS 232C / 20mA–TTY / RS 422/485

Which module variant have you used for test?

For 20mA-TTY interface, have you got any idea to convert the TTY/TTL to RS? 

Will a MAX232 TTL to RS232 converter work?

Regards,

Jin

Hi.

I repeated all steps as video  for CP341, but i can not to do communication.

Modbus Pool write "Bytes Missing Error"

Could you help please