MCC Motor Current

Hi there,

The Simocode is a 'Smart' protection relay for your DOL motor.

As you stated - the Simocode has a Profibus DP interface.

You should never ever have a Star point type connection on Profibus DP. This can cause all sorts of havoc. What you should rather do is sort out your Bus wiring so that all the motors are in serial (i.e. daisy chained). There is a limitation to the amount of nodes (Simocodes) you can put on the DP bus leg - 127.

For a start - www.profibus.com Download the Profibus specifications manuals. This will guide you on the installation requirements for Profibus DP. It will save you a lot of time if you do it right the first time. If you don't - you will regret it as you will pick up spurious interference from incorrect screening/grounding and induction from the electrical cables.

Then goto www.automation.siemens.com You can download the Simocode manual there. It will explain on the diffrent types of configuration and how to set up the data to be passed to and from the Simocode and DCS.

If you have a case where you have multiple motors in different sub stations. You can also look at using Fibre Optic. In this case you will need the OLM (optical link modules) manual from Siemens.

The point to bear in mind - Communications busses must be installed correctly from the onset. If not you will battle for years to get it right.

Just a reminder - Never, ever Star Profibus DP. You will regret it. Not only will you have a lot of noise introduced, but you will have to lower your baud rate so that it it would be faster to walk to the Simocode and take a reading than to use the Bus.

There are devices for parralleling Profibus (Star) - but avoid this. Rather concentrate on getting your bus into a serial (daisy chain configuration) where your flow would be - DP Master - Simocode 1 - Simocode 2 .... Simocode X.

Also make sure that you terminate (use the pull up resistor on the DP connection) the bus at the DP master and at the last node in the line.

Regards,

Craig