Frequently asked questions PROFIBUS

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At commissioning a PROFIBUS-slave I do not see any input data when put and also it is not possible to send data to the device.

For CPUs from the company Siemens only direct access up to 4 bytes is possible. Provided that useful data > 4 bytes are supposed to be read or written, then the access has to be made through the SFC14 (read) and SFC15 (write). Further information can be found in the projection software's help.

How to use the UNIGATE IC PROFIBUS DPV1 5V without driver 485 and how much current can the DC/DC converter provide on the fieldbus side?

Deutschmann uses 1W-DC/DC converter, which can be supplied at 5V with 200mA. On the board without driver we need much less than 50mA of these 200mA, which means 150mA remain for the user. These are certainly adequate.

Changing of the Slave ID via SPS

ID is stored in EEROM.

var LBusState     : Long ;
var L0xE0         : Long ;         moveconst ( L0xE0, 0xE0);

BusStart ;
//Wait ( Bus_Active ) ;

Get ( ReadBusState , LBusState ) ;
if LBusState less L0xE0 then :LoopBusState;   //!!! neu

Which GSD-file is meant for my device?

We distinguish between 2 versions: DPV0 and DPV1. You can tell from the article description which device is in front of you. A »DP« stands for DPV0; a »DPV1« for itself. The UNIGATE IC-DPL and UNIGATE CL is a DPV1-device.

In the download-area of the respective device only that GSD-file, which is valid for the corresponding device only, is placed at your disposal for download.

A DPV1 slave is downwards compatible and it can also operate in the DPV0 mode. Nevertheless, the DPV1 GSD-file has to be used.

DPV0 slave → GSDfile »DAGW2079.GSD«

DPV1 slave → GSD-file »UGIC3218.GSD«

GSD Datei - How to create a different configuration?

Create a configuration

It is also possible in some configuration tools, like Step 7, to use a “Universal Modul”, this is not mentioned in the GSD file. It seams this is a special feature. In this Modul, you can setup every size.

How to set the Slave ID via the Master?

If the Slave ID is set via a Master and the MSB is also set ("Slave address can not be changed anymore"), the flag can only be reset through a "Reset Device" in the configuration mode in WINGATE.

WARNING: With it the EEROM will be re-initialized and the script will be deleted.

How to realize the conversion from Fieldbus ↔ Modbus RTU (Master)?

This proceeding for a UNIGATE CL-PROFIBUS DPV1 is used as an example for all UNIGATEs and the supported Fieldbuses.

UNIGATE CL is supplied with a Universal Script that makes setting the "Modbus RTU (Master)" protocol very simple. A detailed description how to configure the device can be found here.

Note: In case you want to read out the same register several times, then the parameter "Data Exchange" should be adjusted to "On Trigger". In this case the UNIGATE expects the togglebyte in the Fieldbus Master's first byte.


The Fieldbus Master requests (read holding register = 03) the register "4567" with the length of 1 word from the Modbus Slave with the ID=2. The resulting inquiry from the Profibus-Master to the UNIGATE is:

02 03 45 67 00 01

(ID=2, read register=03, register=4567 and length in words high + low=0001)

The UNIGATE converts data to Modbus and adds the checksum (=xx):

02 03 4567 00 01 xx

The UNIGATE receives the following response from the Modbus Slave with the ID=2:

02 03 02 03 E8 xx

(ID=2, read register=03, length in byte =02, value of the register 4567=03E8 and checksum=xx)

The UNIGATE puts the Modbusslave's response on the Fieldbus:

02 03 02 03 E8

Consequently a complete inquiry from the Fieldbus Masters has been converted to Modbus and the Slave's response has been issued to the Fieldbus in turn.

The above proceeding describes the function of the UNIGATE RS, UNIGATE CL with Universal Script and configured Modbus-RTU(Master) protocol as well as our Script examples Modbus-RTU(Master).

There are also applications, in which the UNIGATE is supposed to read out a corresponding register or also the UNIGATE cyclically reads the same regsiter again and again through only 1 byte of the Fieldbus Master. With our UNIGATE SC, CL and IC this is possible without a problem. In these two cases the Script only has to be adapted to this requirement. Please use our Script examples for this.