s7 & profibus -> modbus

marius

Member
Join Date
Apr 2005
Posts
239
well... i'm trying to become wise about how 'Telemechanique LA9P307 PROFIBUS->MODBUS Gateway' works ... i would like to connect S7 CPU units with 15 modbus frequency converters
(to read errors and set some parameters)

i just know about LA9P309:

- support exactly 15 modbus devices
- it is configured using some kind of windows software
- it will generate some .GSD info file (which is according to manual usable with some PL7 sofware i have no experience)
- i may need the switches on modbus side as well (each switch support maximum of 8 modbus device)

so i guess... that i will:
- configure my i/o side on MODBUS
- configure my i/o side on PROFIBUS DP
- save this config into gateway
- import gateway .GSD into step7 project as some kind of i/o device
- and now just by reading/writing channels
on profibus side the gateway will take care about channels
translation into modbus protocol and vice versa
?
... i have also find very few threads with similar content but other hw, so... did anybody of you successfully connected S7 on profibus with modbus device?

thanks for any (in)practical replies :)

(i've spent some time with schneider's technical consultants but the problem is, they do theory, no real work so often and not with s7 of course :) )
 
to connect s7 to modbus slaves u need the to use the following
1-485 communication processor
2-software package for modbus master (or slave in case yr plc is a slave to another network)


in case u are using s7-200 u do not need this package all u need is the add package for microwin
 
well... it's about s7-300, if i will use it this way, it will also allow me to create 'independent' modbus network branch with connection to pc with ability to set any converter parameter i need without making more code
 
What Modus nees

You S7 sofware program for communicate with Modbus slave. Licence program you can bough by Siemen. Modbus Master program. It contex piece what you had to but CP341 backside and Hadware you had to put software download program to CP 341. After that you can communicate with slave by function with use fc7- and and fc8-block's. Modbus Master's CD has excamples program what you can modify.
 
An interesting alternative could be to use an ET200S Profibus station with a CP module 6ES7 138-4DF10-0AB0. It has "Communications processor with RS-232/RS-422/RS-485 connection and Modbus Master driver using 8-byte I/O interface." In other words no need to purchase a loadable driver and a CP341. In effect it would be the same as Telemacanique Profibus to Modbus interface.

Both Siemens and Telemecanique are reputable companies.
If there is no big price difference, then I would pick Telemecanique as they use Modbus for their products in general. So you probably get better support from them.
 
thanks for replies,

i've choose telemechanique, and ordered just it today ... the prices i received while i was outside town, are incredibly different, so much, that with siemens solution is more cost-effective usage of analog outputs for driving ... the second thing is, that configuration should be more easier and i take better personal support from manufacturer :)
 

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