Function Description

The READ_GDATA function is used to read shared data, or Global Data, on a Modbus Plus network.

Global Data is shared between a maximum of 64 stations on the same Modbus Plus network. Each station may write up to 32 integers, which can then be used by all stations on the network. Conversely, each station can read the 32 integers (maximum) of all the other network stations.

The additional parameters EN and ENO can be configured.

FBD representation

Representation:

LD representation

Representation:

IL representation

Representation:

LD Address
READ_GDATA Management_Param, Receiving_Array

ST representation

Representation:

READ_GDATA(Address, Management_Param, Receiving_Array);

Parameter Description

The following table describes the input parameters:

Parameter

Type

Comment

Address

ARRAY [0.. 5] OF INT

Address of the destination entity of the exchange. This address is initialized, before the exchange, with the value of the node on which the station is connected whose Global Data is required.

Example address: ADDR(’0.0.1.10’) corresponds to the station connected to node 10 of the network. The first three figures (0.0.1) correspond to the address of the channel of the Premium Modbus Plus PCMCIA card.

The following table describes the input/output parameters:

Parameter

Type

Comment

Management_Param

ARRAY [0.. 3] OF INT

Exchange management table.

It is not necessary to initialize the length parameter before launching the exchange.

At the end of this exchange, this length parameter (the fourth word) contains the number of bytes that makes up the data produced by the station specified in the address.

The following table describes the output parameters:

Parameter

Type

Comment

Receiving_Array

ARRAY [n... m] OF INT

Word table containing the value of the objects read.