WirelessHART Fieldgate SWG70
Modbus Interface
E Hauser
115
Modbus overview
16.1.2 Modbus in Fieldgate
Fieldgate SWG70 is equipped with both a Modbus serial and Ethernet interface. As a result,
it can be operated in one of the following roles:
• Modbus Serial Slave
• Modbus TCP Slave
A serial or TCP slave can be accessed by one Modbus master only.
Establishing
communication
As a TCP slave, Fieldgate SWG70 will normally communicate with the master via Port 502.
If this port is unavailable, it is possible to specify a secondary TCP/IP port number.
Modbus commands
Fieldgate SWG70 support for Modbus functions is currently as follows:
Modbus RTU
Modbus TCP
Standard compliance "Modbus over Serial Line" V1
"Modbus over TCP" V1
Physical layer
RS-485
Ethernet
Transmission mode RTU (binary mode)
TCP
Baudrates
1200 bit/s, 2400 bit/s, 4800 bit/s,
9600 bit/s, 19200 bit/s, 38400 bit/s,
57600 bit/s, 115200 bit/s
100 MBit/s
Parity
Odd, Even, None
–
Stop bits
1; 1.5; 2
–
Polling address
1...247
–
Port No.
–
502
Capabilities
• Input registers starting at Modbus address 30013
• HART Command 3 dynamic variables mapped into input registers
• 2 input registers map a single HART dynamic variable
• 32bit HART floating point format used
• Status information mapped on dedicated input registers
Function
Function Code
Hex
Function supported
Read discrete inputs
2
0x02
Yes
Read coils
1
0x01
No
Write single coil
5
0x05
No
Write multiple coils
15
0x0F
No
Read input register
4
0x04
Yes
Read holding register
3
0x03
Yes
Write single register
6
0x06
No
Write multiple registers
16
0x10
No
Read/Write multiple register
23
0x17
No