KEPSERVER - MODBUS addressing-help

Hi

I'm trying to establish a MODBUS connection between Panelview plus 1000 (that is the MASTER) and my PC (Slave). In the panel project there's a KEPserver driver running, and in my PC there's a Modbus slave simulator.

I want to simulate some holding registers in my PC, and read them from the panel.
The simulator user guide tells me the parameters that I have to input in the simulator window:

Example:
You want to simulate 20 holding registers from address 40011 (10).
- Slave ID = The ID of your device
- Function = 03 Read Holding Registers
- Address = 10 (Protocol address)
- Quantity = 20

Click to expand...

Now, when I try to insert in kepserver, for example, holding register 40011 , I can't do it because the address is forced to 400011.

How does it works??? What's the meaning of

Address = 10 (Protocol address)

Click to expand...

The root cause of your confusion goes back to the early days of Modicon PLCs and Modbus. The numeral "4" designates 16-bit word memory in Modbus. Originally the limit on type 4 memory was 10,000 words so the address range was from 40000 to 49999. Later that got increased to 100,000 words so the address range became 400000 to 499999. Your KEPserver driver is defaulting your entries to the expanded address range.

The Modbus address 400011 represents the same memory location in a Modbus slave as 40011. It's an offset of 11 words from the start of type 4 memory.

>How does it works??? What's the meaning of
Quote: Address = 10 (Protocol address)

The use of the words 'address' and 'register' get misty, but they are offset from another by one, because of the origin from where the count starts.

Addresses start from zero
Registers start from one

address 00000 = register 00001
address 00001 = register 00002
address 00002 = register 00003
~ ~
address 00010 = register 00011

I left the leading 4 off, because it's the same with input registers in 3xxxxx range. The leading character is only for human use, to identify whether the address/register is for input range (3xxxxx) or the holding register range (4xxxxx).

I'm becoming crazy.... Does anybody know if there is a sample project somewhere? I'm using Factorytalk view 6.0 and a panelviewPlus 1000.....


thank you...