Siemens SENTRON PAC3100, Manual, Page: 27 / 152

Description
3.6 RS 485 interface
SENTRON PAC3100
Manual, 07/2009, A5E02385159B-01
27
● Device firmware updates
● Update of the languages available on the device
The Modbus function codes are listed in the Appendix.
Function
The device operates as a Modbus slave.
Conditions for operation
To use the interface, the device must be parameterized in accordance with the existing
Modbus infrastructure. The communication parameters can be set on the device and via the
Modbus RTU interface.
Default communication settings
In the as-delivered state, the following default values are set:
Table 3- 5 Default Modbus RTU communication settings
Setting Default value
Address 126
Baud rate 19200
Data format 8N2
Response time 0 (automatic)
Response time delay
The response time of the PAC3100 may have to be delayed to enable its operation as a
slave device with devices from other manufacturers on the bus. The PAC3100 can
automatically calculate the response time to suit the baud rate. This automatic calculation is
set at the factory. The delay time is individually adjustable between 1 and 255 milliseconds.
Polarization
Polarization of the RS 485 data lines must be implemented at another point on the bus. The
PAC3100 does not contain polarization resistors.