Facing a problem in reading a holding register that contains the motor current

TIBI68

Dear All,

I would like to take this opportunity and provide you with the fruits of my software development on Modbus RTU Master Communication function blocks over the past years. The function blocks are running on S7-300, S7-400 and S7-400H CPU’s and do not require any additional hardware dongle to be purchased and inserted into the communication processor module. I tried to develop these function blocks from a user perspective in order to make its use as easy as possible for the programmer. Multiple requests to more than one slave connected to the communication processor in a daisy-chain/multi-drop network can be configured within no time.

The following SIMATIC S7 communication processors are supported:

• CP340
• CP341
• CP441-1
• CP441-2

GENERAL INFORMATION & SUPPORT

For installation, connection and interface configuration of your communication processor module kindly follow its respective documentation.

I also advise you to take some time and go through the general information about Modbus provided by our forum membersmiffy. Especially if you are a beginner in Modbus, seek for support or just want to learn more about it.

This software driver is running on several plants in the oil and gas industrysince many years without any known issues. In case you face any problem with the provided function blocks place a comment here in the forum and I will try to give you support. Additionally I would appreciate if users who have already successfully implemented the communication driver into their project will support me in that.

I hope tomake your life a bit easier with this development.

With Best Regards

TIBI68

NEW ! LINKFOR MODBUS RTU SLAVE DRIVER

/tf/WW/en/Posts/114471

MODBUS RTU MASTER DRIVER DOWNLOAD (ATTACHMENTS)

The attached program files need to be retrieved within the SIMATIC Manager.

Currently there is only one manualfor theCP340version but the others are all working in the same way just with different function blocks.

MBMA340.PDF - Manual for Modbus RTU Master for CP340

MBMA340.ZIP -Example projectfor Modbus RTU Master driver for CP340

MBMA341.ZIP -Libraryfor the Modbus RTU Master driver for CP341

MBMA441.ZIP -Libraryfor the Modbus RTU Master driver for CP441-X

MANUAL MBMA340

Attachment

MBMA340.pdf(2086 Downloads)

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Split from MODBUS RTU MASTER FOR CP340/341/441-X (NO DONGLE REQUIRED).

Correct, the MBMAEQ block in this library does not support addressing above 9999. The reason is that it uses the address in order to identify and set the required function code by itself. You are not the first one who ask about this issue and if I remember correctly I made once a block without this limitiation. However, for that version the user need to set the correct function code by himself.

I will search for the block and if you provide me with your email in a PM I will forward it to you for testing.

Best Regards.