Channel Configuration
| Modbus Protocol Type |
Choose Modbus Protocol Type |
| RTU |
Binary message format. 8 bits per data
byte. |
| ASCII |
ASCII message format. 16 bits per data
byte. |
| Ethernet |
Use Modbus/TCP message format. |
| Modbus Protocol Mode |
Choose Modbus Protocol Mode |
| Master |
IOServer wil initiate all requests. |
| Slave |
IOServer will wait for and response to
requests. |
| Buffer Size |
Maximum of frame. 256 is the standard
maximum frame size. |
| Initialization |
The initial command sent to the device to check if the
device is online. In the form "BitAddress, Function Code, BitCount".
The default value is "0,3,16".
| Function Code |
Modbus Address |
Data Type |
| 1 |
0xxxx |
Output Coils |
| 2 |
1xxxx |
Input Status |
| 4 |
3xxxx |
Input Registers |
| 3 |
4xxxx |
Output Registers |
| 7 |
E.x |
Exception Status |
|
Device Configuration
| Address |
Device address of slave. |
| Register Address Size |
Size of each register in the PLC. The default is two
bytes per register location. |
| Non standard 1 origin
addressing |
Add 1 to address when requesting data. |
| Signed Integer |
Treat all integers as signed. |
| 0 Origin addressing for bits in Registers. |
Bits in registers are numbered 0 to 15. The default
numbering is 1-16. |
| Reverse Bits in Registers |
The bits in registers are reversed |
| 32 Bits Value Byte Ordering |
Long value (4 bytes) byte ordering of device.
Device.40001,I4 will read the two registers at 40001 as a 32 bit
signed integer value.
|
| 32 Bits Floating Point Byte Ordering |
Single Precision Floating point numbers byte ordering of device.
Device.40001,R4 will read the two registers at 4001 as a 32 bit
floating point value.
|
| 64 Bits Floating Point Byte Ordering |
Double Precision Floating point numbers byte ordering of device. |
Variable Types
Modbus Channel Master Mode
| .Master Value |
|
| 255 |
Master Mode, issue read and write function codes to slave |
| 0 |
Issue write function code to slave, accept write
function code from slave |
| n Seconds (1 to 254) |
Issue read function code to slave for next n seconds, issue
write function code to slave, accept write function from slave |
Modbus Channel Slave Mode
| .Master Value |
|
| 255 |
Slave Mode, accept read and write function codes from master |
| 0 |
Accept read and write function codes from master |
| 1 |
Accept read and write function codes from master, issue
write function code to slave |
Modbus Function Codes Supported
1, 2, 3, 4, 5, 6, 7, 15 and 16
Performance
IOServer running on a Pentium 4, 2.8 GHz PC under Windows 2000 Advanced
Server reading
from a remote device.
| Protocol |
Requests per second |
| TCP/IP, 2 bytes per request |
2180 |
| TCP/IP, 250 bytes per request |
1392 |
| TCP/IP, 1450 bytes per request |
506 |
|
