313
Modbus I/O Access
Modbus TCP Application
If you have a Modbus RTU or Modbus ASCII program, you can access the I/O by connecting to the
IOLAN over the network.
Modbus I/O Access
The section defines the function codes and registers you will need to access the I/O through Modbus
TCP, Modbus serial, or Modbus serial/TruePort.
Function Codes
The following function codes are supported by the IOLAN:
z
01
read coils
z
03
read multiple holding registers
z
04
read input registers
z
05
write coil
z
06
write single register
z
08
diagnostics (echo the request)
z
15
force multiple coils
z
16
write multiple registers
There are four Modbus data models:
All coil/register values are in decimal.
Discrete Input
Not used
Coils
Digital Input (DI), Alarm state for DI, Digital Output (DO). All coils
are Boolean values and are 1 byte.
Input Registers (IR)
Analog Input (AI), Alarm state for AI. All Input Registers are 2 bytes
long.
Holding Registers
Status (R), Control value (R/W or W). Holding Registers with _ENG
registers are 4 bytes long, all other Holding Registers are 2 bytes
long.
Network
IOLAN
pe
rle
PC running a
Modbus RTU
or ASCII
Application
UID: 15
I/O Digital
Output
Power
Содержание IOLAN MDC
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