Technical data

W&T

displaying an analog measurement value: <w&t_tags=m1>.

Likewise the tags are applicable to e-mail etc.

Using the above tags you can access the free memory as

follows: <w&t_tags=modbus:rbxHH>, whereby the syntax after

the colon corresponds to the syntax for embedded tags. This

means each byte can be read by the byte. The memory can be

read out by the word or in double words. Big Endian format is

used:

In addition, by using GET /modbusreg?PW=& you can read out

the entire data contents (128 bytes) at one time. Here the

device constructs an ASCII string which starts with „modbus“,

followed by „;“ and the data as ASCII characters (1 byte is shown

with 2 ASCII characters.), also separated by „;“.

Example: „modbus;00;00;00;...“

If „modbus“ is read, but then after the „;“ an „OFF“ follows, this

indicates that the device is not configured for Modbus. This

criterion can be used on the user page.

The user page can be adapted for the browser so that the

stored data can be displayed as desired. By adapting the

function CommandLoop() and updateDisplay(ReceiveStr) you

can refresh the Modbus values cyclically.

3.10.6 Modbus memory distribution

In the following tables you can see the memory ranges (1-, 16-,

32-bit) for the Web-IO Analog In/Out which can be accessed

using Modbus TCP. The green columns indicate which function

codes can be used to read the addresses. The red columns

show the function codes used for writing to the registers. The

yellow column shows which and how many elements are

supported by the device.