User manual

105G Wireless Gateway User Manual
Elpro_man_105g_1.18.doc Page 84
The Profibus address can be set in the “Fieldbus Config” screen or via the rotary switch on the
end-plate of the module- valid slave addresses are 1 – 126. If the “Enable Rotary Switch” box is
not selected, then the address entered in the program will be used and the rotary switch value
ignored. If the “Enable Rotary Switch” box is selected, then the address entered in the
configuration program will be ignored and the rotary switch read on start-up of the 105G.
The Profibus interface has 416 bytes, of which 244 can be used as input bytes, or 244 can be
used as output bytes.
Note: For bit transfers, the bit offset is counted from the least significant bit (LSB) of the byte
(with bit 0 being the LSB) - if you transfer 3 bits with a bit offset of 5, then you will transfer bits
5-7 of the byte. This is different than the Ethernet unit which counts the offset from the most
significant bit - refer next section.
The fieldbus write mapping in the example below transfers 5x16-bit registers (words) from the
radio interface to the fieldbus interface. Care should be taken that the Profibus Master device
does not attempt to access more I/O than has been setup via fieldbus mappings. I.e. in the
example below, the Profibus Master can read a maximum of 5 words (10 bytes) only from the
105G.
An application note for configuring a Siemens S7 PLC to communicate with a Profibus
105G can be downloaded from the ELPRO Technologies web-site www.elprotech.com