How are Arrays addressed in drivers like Modbus and Siemens?

Most drivers in TOP Server provide the ability to define arrays of contiguous registers of the same data type.

1. The standard drivers support 1 and 2 dimensions arrays only
2. The individual elements of an array cannot be addressed directly.
3. Sub arrays of data within the array are not allowed and you cannot create an array of arrays.

For reference, when creating an array in a standard driver, the array dimensions are specified using square brackets, [ and ]. The address for the array is defined as Register[row][col].

In the 4x4 array example below, array is referenced as DB0W0 [4][4].

The data is returned as a variant array. The OPC Quick Client will display the data in the following format: [73,78,84,255][256,257,258,259][9,10,11,12][13,14,15,16].

A 4 X 4 array in a Siemens S7-300.

73	78	84	255
256	257	258	259
9	10	11	12
13	14	15	16

In the 4x4 array example below, array is referenced as DB0W0 [1][16].

The data is returned as a variant array. The OPC Quick Client will display the data in the following format: [73,78,84,255,256,257,258,259,9,10,11,12,13,14,15,16].

A 1 X 16 array in in a Siemens S7-300

73

78

84

255

256

257

258

259

9

10

11

12

13

14

15

16