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

Help with Modbus RTU

Created by: automatizzando at: 3/11/2011 8:51 PM (19 Replies)

Rating (0)

Thanks 11

Result pages:: |; 1 | 2; |

20 Entries

Entries per page: 10 | all

3/11/2011 8:51 PM	Rate (0)
automatizzando Bronze Member Joined: 3/11/2007 Last visit: 3/20/2025 Posts: 226 Rating: (13)	I made a little test to communicate with a Modbus RTU network analyzer electric Lovato. But I can not in any way to read the records of the analyzer. For communication using a RS232 to RS485 converter, which the PC>>> Analyzer it works fine. Could you give me a help please? Thanks Attachment Test_1 modbus RTU.zip (284 Downloads)
	Last edited by: automatizzando at: 3/11/2011 8:58 PM
Suggestion To thank Quote Answer

3/15/2011 4:32 PM	Rate (0)
automatizzando Bronze Member Joined: 3/11/2007 Last visit: 3/20/2025 Posts: 226 Rating: (13)	I was abletoestablishcommunicationbetweenthemasterandslave. Nowthe readingsofsomeregistersinModbusRTUmodebetween anS71200(MASTER)andathird-party device(slave). I have noticedthough thatifsomeof theregistersofthe slavethat I question,assuming the valuezero,thecommunication breaks down,and iftakinganyothernon-zero value,the communication takes placeregularly.So much sothatby varyingthevalueof theregistersofthe slavemanually,I clearly seechangeinthe masterrecordsread,in exactlythe valueenteredin the slave. Also,whentheportregisters"indicted"to zero,the appropriateblock outputgoesto "1"toindicate the presenceof errors. The errorsthatInotedare: Error80E3 Error80E2 Error8380 Can youtell mesome adviceonwhatcouldbecausing this? Thanks

Suggestion To thank Quote Answer

7/11/2013 3:34 PM	Rate (0)
Juan.Mechatronic Posts: 98 Rating: (6)	Have you solved this situation? I need to make a Modbus RTU communication too but I can´t conect with a Third party Inverter. Can you help? Thanks In advanced
Juan.Mechatronic Posts: 98 Rating: (6)
Suggestion To thank Quote Answer

7/11/2013 4:54 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 3/24/2025 Posts: 6863 Rating: (1366)	Juan. Mechatronic Have you solved this situation? I need to make a Modbus RTU communication too but I can´t conect with a Third party Inverter. Can you help? Thanks In advanced Hello, What type of controller do you work on and what is the communication processor? If you project, upload.Then make it clear what kind of Modbus function yo trying to implement.Online view of the block if possible! Best regards Hamid Hosseini
	Last edited by: hdhosseini at: 7/11/2013 4:56 PM Demo Channel on Youtube
Suggestion To thank Quote Answer
This contribution was helpful to 2 thankful Users Lucky123 Juan.Mechatronic

7/11/2013 4:58 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	Hello Juan, do you use S7-1200 as ModbusRTU master? Do you get any error message? Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users Juan.Mechatronic

7/11/2013 5:09 PM	Rate (0)
Juan.Mechatronic Posts: 98 Rating: (6)	Hey all, I have a S7 1214C DC/DCDC with a Cm 1241 RS 422/485 The inverter is Mitsubishi FR D700 I have no error messages but the Master block never shows Done Bit, and never gets data on Data_PTR. I configured the CM module on 485 (2 Wire, Hal duplex), The inverter has 4 Pin so is Full Duplex. That can be a posible problem which pins do I have to conect? And which Data_PTR type do I have to send for this inverter? Thanks in advanced, I can´t upload my project by now cause I'm not on my own PC. Best Regards
Juan.Mechatronic Posts: 98 Rating: (6)
Suggestion To thank Quote Answer

7/11/2013 5:20 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	Hello Juan, no, it is not possible that one communication partner uses 2-wire and the other one 4-wire connection. Then you should use a converter. Please note: the outputs are displayed dynamically, so you can't see them with online monitoring. You should evaluate them in your program. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users Juan.Mechatronic

7/11/2013 5:30 PM	Rate (0)
Juan.Mechatronic Posts: 98 Rating: (6)	Kaulquappe Hello Juan, no, it is not possible that one communication partner uses 2-wire and the other one 4-wire connection. Then you should use a converter. Please note: the outputs are displayed dynamically, so you can't see them with online monitoring. You should evaluate them in your program. Regards, Kaulquappe But seeing on the internet, some applications just conect, S+ with R+, and S- with R-;? In this case cause my CM is 422/485 can i change it to 422 full duplex and can works better, or definitely is better use a conversor?. I said, that bit done never change true cause a use a variable to monitor this bit.
Juan.Mechatronic Posts: 98 Rating: (6)
Suggestion To thank Quote Answer

7/11/2013 5:43 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 3/10/2025 Posts: 1557 Rating: (540)	You can use either RS422 or RS485, but each device must use the same interface. RS485 uses 2 wires (TX/RX+ and TX/RX-). You connect:- TX/RX+ ----------- TX/RX+ (or possibly TX/RX- if it doesn't work) TX/RX- ------------ TX/RX- (or possibly TX/RX+ if it doesn't work) Sometimes, it may be that you have to reverse the +/- (shown in brackets above) to get it to work RS422 uses 4 wires. TX+, TX-, RX+ and RX-. For this you connect:- S7 Partner TX+ ----------- RX+ (or possibly RX- if it doesn't work) TX- ------------ RX- (or possibly RX+ if it doesn't work) RX+ ----------- TX- (or possibly TX- if it doesn't work) RX- ------------ TX+ (or possibly TX+ if it doesn't work) Again, sometimes it may be required to reverse the +/- (shown in brackets above)
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users Juan.Mechatronic

7/12/2013 3:48 PM	Rate (0)
Juan.Mechatronic Posts: 98 Rating: (6)	smiffy You can use either RS422 or RS485, but each device must use the same interface. RS485 uses 2 wires (TX/RX+ and TX/RX-). You connect:- TX/RX+ ----------- TX/RX+ (or possibly TX/RX- if it doesn't work) TX/RX- ------------ TX/RX- (or possibly TX/RX+ if it doesn't work) Sometimes, it may be that you have to reverse the +/- (shown in brackets above) to get it to work RS422 uses 4 wires. TX+, TX-, RX+ and RX-. For this you connect:- S7 Partner TX+ ----------- RX+ (or possibly RX- if it doesn't work) TX- ------------ RX- (or possibly RX+ if it doesn't work) RX+ ----------- TX- (or possibly TX- if it doesn't work) RX- ------------ TX+ (or possibly TX+ if it doesn't work) Again, sometimes it may be required to reverse the +/- (shown in brackets above) So in my case have this 2 situations (Acording to module RS422/485): S7-1200 (RS-485)----------------------- partner RS 485 (RxD/TxD+) RDA (RxD/TxD-) SDB SDA RDB S7-1200 (RS-422)----------------------- partner RS 485 TX+ RDA TX- SDB RX+ SDA RX- RDB How can I conect? Or asKaulquappesaid I need to use a converter on any case?
Juan.Mechatronic Posts: 98 Rating: (6)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on