MODBUS RTU and DeviceNet

[pszczepan 2]

Hi ! I will have many temperature sensors. I could use some as MODBUS RTU slaves - less cables, but I cannot find any DeviceNet module - Modbus RTU Master - is there any? It is worse idea, but I could also use Modbus RTU Master, which could be some device for CJ1M - the problem is length of cable - I would have to install two wires to another building - one for devicenet, one for Modbus RTU. In this case what device I need? Thanks Pawel

[pszczepan 2]

You think that if I use DeviceNet module DRT1-232C2 and converter RS232 ->RS485 I will be able to implement Modbus RTU protocol to establish communication with MODBUS RTU slave devices (temperature sensors)? Thanks Pawel

[PdL 71]

So Pawel, let me get this straight. In short you want to connect Modbus slaves to a Devicenet network? Something like this? 4th hit in Google if you search for "devicenet modbus".....

[pszczepan 2]

When I read some topics about modbus at the Omron forums there are same examples how to communicate with modbus slave/master through SCU card in CJ1M - you need to use CX-protocol to communicate. This gateway is a good idea, but I am not sure how I could control data in Modbus network by program in PLC through devicenet. I can have problem to get any support for it - it is Schneider product and I am not really familiar with it. Before I make a decision I have to be sure I will do it. Does anyone used such a device and can give any example, advise e.t.c ? thanks - all the time something new

[pszczepan 2]

Hello ! I read carefuly manual for LUFP9 gateway and it is mostly dedicated for inverter made by Telemecanique and one LUFP9 can be master for max 8 slaves. Modbus RTU can have 255 addresess - so 8 is not enough for me - probably I will have more slaves. I found that: 1782-JDM-2 : http://www.wrcakron.com/devicenet.html It looks good and the manual is more useful. I sent email to producer how I can purchase it in UE, but I have also tech question. I have some FB for PLC to send a modbus RTU command to slave. I have idea how to implement it if I use SCU card, but I am not sure how I should use this FB to send a command to Modbus RTU slave, which is connected to this gateway. Maybe you know some tip, any clue? thanks Pawel