Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

CP341 Modbus Slave

Created by: Import-User-1 at: 11/5/2009 3:09 PM (23 Replies)

Rating (1)

Thanks 3

Result pages:: |; 1 | 2 | 3; |

24 Entries

Entries per page: 10 | 20 | all

11/5/2009 3:09 PM	Rate (0)
Import-User-1 Posts: 3609 Rating: (29)	Import of a Technical Question of an User Lex wrote: Dear Experts, Please to help me about CP341 Modbus Slave function, i used the Modbus Slave on CP341 for support Modbus register 402001 - 402080 but have error exception happen, But when i used modbus scan tools read 402001 amount 10 register is work, But when i try to get 402001 amout 30 or gather but not work (Error Exception from Modbus Slave) Please to advice i you have solution about CP341 on MBSlave function. Regards,
Import-User-1 Posts: 3609 Rating: (29)
Suggestion To thank Quote Answer

11/6/2009 9:45 AM	Rate (0)
Robster Gold Member Joined: 5/28/2008 Last visit: 10/23/2024 Posts: 1343 Rating: (141)	I can believe there is a data limit per Modbus-Telegram. Try to split your requests, then it should work. regards

Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users J_Bell

11/6/2009 10:11 AM	Rate (1)
how come Posts: 382 Rating: (47)	Hi, Add on to what Robster said, I hope the following attach can give you some help! 1] you need to install the PtP software 2] remember the install the license key to the CP341 3] configure the CP341 as slave and see my setup examples from my examples i am using DB150 & 151 using FC03,04,etc. You have to define the DB and FCs that suits your application. Hope this helps with regards, how come Attachment To Lex.zip (315 Downloads)
how come Posts: 382 Rating: (47)	Last edited by: how come at: 11/6/2009 10:16 AM
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users J_Bell r2407

11/7/2009 4:36 AM	Rate (0)
Lex Posts: 19 Rating: (0)	Thank you very for every answer. Yes , I try setting following your suggestion , But on the Modbus slave range 402001 amount over 24 register range is same exception error. I not sure this a limitaton of Modbus Slave function or not? If you have any solution please to advice. Regards, Lex.
Lex Posts: 19 Rating: (0)
Suggestion To thank Quote Answer

11/7/2009 4:13 PM	Rate (0)
how come Posts: 382 Rating: (47)	Hm....., to me 24 registers = 48 bytes. That's not much or large amount or being limited by CP341. Is it possible you can post your project here? Let me try out using my modbus scan software. with regards, how come
how come Posts: 382 Rating: (47)	Last edited by: how come at: 11/7/2009 4:15 PM
Suggestion To thank Quote Answer

11/7/2009 6:18 PM	Rate (0)
Lex Posts: 19 Rating: (0)	Hi, How come. O.K. how come ,And this a PRG for Modbus Slave, Please to advice. And to explain my problem, to observe when i try to get the Modbus data from 400001 to 400100 amount(100 registers) not found the problem everything is O.K. But when i get the 402001 amout gather 20 registers is have error exception.. Please to advice. Lex. Attachment MBSlave.zip (295 Downloads)
Lex Posts: 19 Rating: (0)
Suggestion To thank Quote Answer

11/9/2009 4:42 AM	Rate (0)
how come Posts: 382 Rating: (47)	Hi Lex, So sorry that I havn't test your program at the moment as I am not in office [now onsite commissioning]. I have open your program. I notice that your slave protocol setup for FC3,06,16 & FC04 set as DB1. But in your program there is not DB1? I would like to know your 400001 to 400100 amount(100 registers) is from which DB in your program? Is it DB42? And the next 20 registers (402001) also from DB42? Let me try my best to explain first. For example, DB42 is the data block that is ready for the modbus master to read from the slave and the master is using Function Code 03. Thus in your protocol setup under the tab FC03,06,16 should set to DB42. For example, DB43 is the data block that is for the modbus master to write to the slave and the master is using Function Code 04. Thus in your protocol setup under the tab FC04 should set to DB43. I have also attach a modbus scan software which i used to test my program. I hope this can give you some help first. with regards, how come Attachment Installer_CAS Modbus Scanner.zip (318 Downloads)
how come Posts: 382 Rating: (47)
Suggestion To thank Quote Answer

11/9/2009 5:45 PM	Rate (0)
Lex Posts: 19 Rating: (0)	Very Thank for your suggestion, and for your software scaning tools. So if you looking on my program , i assign the DB80 for used in the instance data of the FB80, And DB1 for Modbus Function-3 , and i create the data struc of DB1 is array of integer size 0..1023 for DB1, and i recopy DB1 to DB2 , DB3, DB4, DB5 for modbus slave registers, And i try to scan data on register 400001 - 400511 ,the Modbus data is correct responsed, But if when i re-scan MBSlave data 4:480 - 4:510 or to last register is not responsed from MBSlave. And the same case when i try scan on the 4:2001 - 4:2024 is not responsed or on the same of exception from slave, I not sure is a error from the FB80 Modbus function or not? Or is a incorrect setting from my program. Please adviced Regards, Lex.
Lex Posts: 19 Rating: (0)
Suggestion To thank Quote Answer

11/11/2009 4:02 AM	Rate (0)
how come Posts: 382 Rating: (47)	Hi Lex, I spare some time look through your modbus slave setting for OB1 and OB100,you didn't set the initialization of mobus slave correctly. See my attach for the setup. One more thing, did you do any changes in FB80?? FB80 surpose to be a protected block in default in step7 function block libraries!!Did you remove the protection and did some changes? It should be used as default with the instance DB please do not change it. I suggest you delete the current FB80 and recall the block from the step7 libraries again. I will send you a sample program later. Hope this helps! with regards, how come Attachment To Lex1.zip (241 Downloads)
how come Posts: 382 Rating: (47)
Suggestion To thank Quote Answer

11/11/2009 4:58 AM	Rate (0)
how come Posts: 382 Rating: (47)	Hi Lex, Here is the sample program. Infact this example also can be obtained from step7 under sample projects. I have modified it simliarto your case. Fill in thevalues in DB1 that you wish for themasterto read. Download to your PLC. Put aside all other logic function and just test this program alone with the modbus scan tools that i had sent you previously. If this work as what you want, then you implement/integrate the blocks to your existing program. Frankly speaking i have not testedmyself as ihave no chance to go back office yet stillout field commissioning my project.The sample from siemens should work with just slight modification to your CPU type. I don't think the CPU will result the program not working. good luck! with regards, how come Attachment MBSLave Sample.zip (300 Downloads)
how come Posts: 382 Rating: (47)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on