VEGA VEGACOM 557 Modbus protocol - Manual (Page 38)

38 VEGACOM 557 Modbus
Transfer switching status to RTU mode
Independent of the connected VEGA signal conditioning instrument (VEGAMET or VEGA-
LOG), the transmission of the switching status via 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“.
Procedure 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 is stated in the table in supplement B.
Example for data from VEGAMET 515:
The switching status 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) Procedure with Modbus-Master-simulation (e.g. PC) Procedure with Modbus-Master-simulation (e.g. PC)
In case the enquiry of the switching status 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 demonstration
should explain the communication processes between Modbus-Master and VEGACOM 557
on the Modbus.
Example for switching status of VEGALOG:
The switching status of the VEGALOG-AR cards should be outputted on module #3 and #4. 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:
Output: 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
Data transmission with Modbus RTU