Vega VEGACOM 557 Modbus protocol Bedienungsanleitung PDF herunterladen (Seite 45)

VEGACOM 557 Modbus 45

Data transmission with Modbus ASCII

Transfer switching conditions in ASCII mode

Independent of the connected VEGA signal conditioning instrument (VEGAMET or VEGA-

LOG), the transmission of the switching conditions via the Modbus is always made acc. to the

same procedure via the function code 01 "Read Coil Status“ or optionally via function code 02

"Read Input Status“.

Proceeding with Modbus-Master Modicon or Freelance 2000

When using an AEG-Modicon or a Freelance 2000 from Hartmann & Braun as Modbus-Master,

these systems take over the communication to the Modbus. In this case, only the respective

function enquiry "Read Coil Status“ or "Read Input Status“ must be programmed in the PLC

and the required parameters such as Slave address, start register and number of register

must be stated. The conversion of the output addresses in VEGALOG or input/output ad-

dresses in VEGAMET to the input registers of the PLC are given in the table in supplement B.

Example for data from VEGAMET 515:

The switching conditions of VEGAMET #3 (relay outputs 1 and 2 and fail safe relay) should be

collected. In addition, the status bit for the outputs should be read in to make sure that the

data are valid. The slave address of VEGACOM 557 is set to 1.

Parameter setting for function enquiry "Read Input Registers“:

- Slave address = 1

- Register bit address (start) = 10.041 (or 040 on Freelance 2000)

- Number of register bits = 8

Procedure with Modbus-Master-simulation (e.g. PC)Procedure with Modbus-Master-simulation (e.g. PC)

Procedure with Modbus-Master-simulation (e.g. PC)

In case the data enquiry should be made via a Modbus-Master-simulation, this can be done,

for example, via a self-written communication driver using the "Function code 01 = Read Coil

Status“ or "Function code 02 = Read Input Status“. The following diagrams 5.10 to 5.11 should

explain the communication processes between Modbus-Master and VEGACOM 557 on the

Modbus.

Example for switching conditions of VEGALOG:

The switching conditions of the VEGALOG-AR cards on module #3 and #4 should be read out.

In addition, the respective status bits for the output cards should be read out to make sure

that the data are valid. The slave address of VEGACOM 557 is set to 1.

Actual switching conditions on VEGALOG are:

Outp.: 1 2 3 4 5 6 7 8 9 10 Status

AR card #3 ON ON ON ON OFF OFF OFF OFF OFF OFF OK

AR card #4 ON ON ON ON OFF OFF OFF OFF OFF OFF OK

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Vega VEGACOM 557 Modbus protocol Bedienungsanleitung Seite 45