Skip to Content

SiePortal

The integrated platform for your product selection, buying and support workflow - bringing together Industry Mall and Online Support.

SiePortalDeutsch

Search

Home
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menu temporary not available
- Menue temporary not available
- {{item.title}}

Products & Services
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Support Support
{{(apiData.Support | filter:{'rank':1}:true)[0].title}} Support
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
MySiePortal MySiePortal
{{(apiData.MySiePortal | filter:{'rank':1}:true)[0].title}} MySiePortal
- Menu temporary not available
- Menue temporary not available
- {{item.title}}
Cart ({{apiData.CartCount}})

Navigation

CP341 and slave communication error

Created by: Assassou at: 7/9/2013 9:22 AM (10 Replies)

Rating (0)

Thanks 2

Result pages:: |; 1 | 2; |

11 Entries

Entries per page: 10 | all

7/9/2013 9:22 AM	Rate (0)
Assassou Posts: 4 Rating: (0)	Dear experts, I have three S7-400, H architecture stations to manage 3 power units. Each CPU is communicating through Modbus master (CP341) with two slaves (Tension and speed governors). Now one of the slaves of the Station #3, the speed governor displays Network error mean while CP341 reports no error. No SF led, no Tx and Rx led. No error in CPU nor CP341 buffer. I have tried to solve the problem with this: 1.Checking the program shows that FB7 and FB8 were not programmed. Even on Station #2 and #1, these FB's are not programmed but the stations are working fine. 2.I disconnect the comm cable between slaves and CP341: no error reported! 3.I remove all other modules on the rack and left CP341 alone: still no error. Note that the 2nd slave comm leds also are not blinking. Please, help! I am in serious trouble
Assassou Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

7/9/2013 9:39 AM	Rate (0)
SolutionFinder Posts: 559 Rating: (87)	Assassou Dear experts, Now one of the slaves of the Station #3, the speed governor displays Network error Please, help! I am in serious trouble I couldn't get your point. What do you mean by network error? Where you have checked this error? If you want help for modbus programming of CP341 then just go to sample program in simatic manager itself, there you can find very good sample projects for modbus master as well as slave programs. This you can get only after installing the Software came with CD of CP 341.
SolutionFinder Posts: 559 Rating: (87)
Suggestion To thank Quote Answer

7/9/2013 9:43 AM	Rate (0)
Amit_86 Platinum Member Joined: 3/18/2008 Last visit: 12/8/2023 Posts: 1750 Rating: (272)	Assassou Dear experts, I have three S7-400, H architecture stations to manage 3 power units. Each CPU is communicating through Modbus master (CP341) with two slaves (Tension and speed governors). Now one of the slaves of the Station #3, the speed governor displays Network error mean while CP341 reports no error. No SF led, no Tx and Rx led. No error in CPU nor CP341 buffer. I have tried to solve the problem with this: 1.Checking the program shows that FB7 and FB8 were not programmed. Even on Station #2 and #1, these FB's are not programmed but the stations are working fine. 2.I disconnect the comm cable between slaves and CP341: no error reported! 3.I remove all other modules on the rack and left CP341 alone: still no error. Note that the 2nd slave comm leds also are not blinking. Please, help! I am in serious trouble Hello, I think problem in your Program so double check it. If possible , please attach your Program.
	VANDE MATARAM.....
Suggestion To thank Quote Answer

7/9/2013 9:50 AM	Rate (0)
DS SURESH KUMAR Bronze Member Joined: 4/17/2012 Last visit: 2/25/2025 Posts: 474 Rating: (10)	Assassou Dear experts, I have three S7-400, H architecture stations to manage 3 power units. Each CPU is communicating through Modbus master (CP341) with two slaves (Tension and speed governors). Now one of the slaves of the Station #3, the speed governor displays Network error mean while CP341 reports no error. No SF led, no Tx and Rx led. No error in CPU nor CP341 buffer. I have tried to solve the problem with this: 1.Checking the program shows that FB7 and FB8 were not programmed. Even on Station #2 and #1, these FB's are not programmed but the stations are working fine. 2.I disconnect the comm cable between slaves and CP341: no error reported! 3.I remove all other modules on the rack and left CP341 alone: still no error. Note that the 2nd slave comm leds also are not blinking. Please, help! I am in serious trouble Hi, In modbus slave device wiring may be wrong or modbus slave have no power.. check it

Suggestion To thank Quote Answer

7/9/2013 10:31 AM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	Assassou 1.Checking the program shows that FB7 and FB8 were not programmed. Even on Station #2 and #1, these FB's are not programmed but the stations are working fine. 2.I disconnect the comm cable between slaves and CP341: no error reported! 3.I remove all other modules on the rack and left CP341 alone: still no error. Hello Assassou, 1) with Modbus slave you need the call of FB80 not FB7 and FB8. 2) I think you use RS485. With RS485 it is not possible to detect BREAK. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
Suggestion To thank Quote Answer

7/9/2013 10:51 AM	Rate (0)
Assassou Posts: 4 Rating: (0)	Thanks a lot! i am new in PLC issues so please be patient, The network error is display by the speed governor on his own screen. CP341 is Modbus master (this is display in the CP 341 parameters dialog box) not slave. Yes, i use RS422/485 Can it be problem in the program since the station runs for more than 2 years without any problem. I cannot figure if the CP341 is bad and need replacement. And why is that no error is reported. Is it because FB7&8 are not programmed? Thank you again
Assassou Posts: 4 Rating: (0)	Last edited by: Assassou at: 7/9/2013 10:53 AM
Suggestion To thank Quote Answer

7/9/2013 1:02 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	Hello Assassou, so you have got the same configuration three times: S7-400H and ET200 with CP341 with one slave. And one of these systems doesn't work anymore. Please correct me when I'm wrong. When the S7 acts as Modbus master, a call of FB7 and FB8 is required. I wonder how it has ever been running without. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
Suggestion To thank Quote Answer

7/9/2013 3:27 PM	Rate (0)
Assassou Posts: 4 Rating: (0)	Kaulquappe Hello Assassou, so you have got the same configuration three times: S7-400H and ET200 with CP341 with one slave. And one of these systems doesn't work anymore. Please correct me when I'm wrong. We have S7-400H and ET200 with CP341 with two slaves three times The 02 others stations are still running without FB7&8, it's really hard to understand. I have made and arrangement with my boss to stop one of running stations and try the "bad" CP341 on it. I will come back with fresher news.
Assassou Posts: 4 Rating: (0)
Suggestion To thank Quote Answer

7/9/2013 4:17 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	Hello Assassou, do you probably use the special PCS7 library blocks for Modbus RTU communication? The Modbus block is called S7HMODM3. Then you can contact function.blocks.industry@siemens.com for further help. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
Suggestion To thank Quote Answer

7/22/2013 1:07 PM	Rate (0)
Assassou Posts: 4 Rating: (0)	My problem is solved. Thanks to all. 1-I reloaded DB183, DB184 (data instance of FB7 and FB8 i think - correct me if not), DB186 and DB187. Then i can now communicate with on slave (Voltagegovernor), Tx/Rxon CP341 start blinking. At this stage, no communition with the second slave (Speed governor) who is displaying on his own screen "Network fault". 2- There is a RS422/485 to Ethernet converter (ACKSYS Cometh-field-rd) between CP341 and the 2nd slave we assume is not working (although no Fault LED is lighted). We decided to change the network card of the 2nd slave in order to communicate directly with CP341 withough need of ACKSYS Cometh-field-rd converter. Then BINGO!!
Assassou Posts: 4 Rating: (0)
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users Kaulquappe O_Moderator

|

Share this page:

Share this page on...

Follow us on