Good evening,

I'm after a little bit of advise / help with the relativly new SINAMIC V90 servo system, after speaking to tech support in Manchester I've been told in the first person in the UK to use the V90 power and communicate to a PLC via Modbus Comms , I have a 6SL3210-5FE10-4UA0 (V90 0.4kW unit) and a S7-1215c PLC and a Communications Module CM 1241 (6ES7241-1CH32-0XB0). This system has its own config software V-Assistant, ISO is not intergrated into TIA (Totally not as intergrated) nor is it in starter, has anyone else set up comms or even know where the device description file are? Have any application expanles (The Ones on Siemens Are Not with comms only I / O) ?? Ideally i want to use a standard telegram sending over basic commands' Run, stop speed ref, position setpoints and run a constaint position move step. Anyone out there done this ??

Thanks in advance!

Hello Gaz_C:

First here is a manual describing the use of Modbus RTU with a V90 servo drive:

https://support.industry.siemens.com/cs/attachments/109479016/OnlineHelp_V90_en_US_en-US.pdf?download=true

See section 4.5 to understand the Modbus mapping of the V90. Use Modbus Function 3 to access (read) and Modbus Function 15 to write to  the registers with addresses in the 40000 range.

Modbus does not allow a standard telegram format. You must locate and request the specific registers you require (in read and write Modbus functions); generally you try to request the largest possible range of registers to your PLC m,aster, then pick and choose the values you need in your PLC communication DB.

Just in case you might need an introduction or a refresher on Modbus communications, I strongly suggest you read this thread by our friend smiffy:

Modbus General Description

In addition, the following FAQ addresses Modbus RTU programming blocks on a S7-1200:

How do you establish a MODBUS-RTU communication with STEP 7 (TIA Portal) for the SIMATIC S7-1200?

And here is an Application Example you might find useful (it is for a V20 servo drive, but you should find parallels in the communication functions):

SINAMICS V: Speed Control of a V20 with S7-1200 (TIA portal) via USS® protocol/MODBUS RTU with HMI

Hope this helps,

Daniel Chartier

New question published by pakplc is split to a separate thread with the subject V90 Servo Comms: Reading data using MB_Master_DB is not responding.

Best regards
CS Moderator