User manual

105G Wireless Gateway User Manual
Elpro_man_105g_1.18.doc Page 54
Read/Write Mappings
The mappings can be “read” or “write” mappings. A Read mapping is a request sent to another
105G to return a block of values. A Write mapping is a message sending a block of values to
another 105G. A Read mapping from 105G#2 to 105G#3 could be the same as a Write mapping
from 105G#3 to 105G#2 (that is, in the reverse direction) - except the Read mapping is initiated
from #2 and the Write mapping is initiated from #3.
Word/Bit Mappings
Read and Write mappings are also selected as Word or Bit mappings - that is, you can select a
Read Word mapping or a Read Bit mapping and you can select a Write Word mapping or a
Write Bit mapping. “Word” refers to a complete 16-bit register value; “Bit” refers to the value
of the most significant bit of a register - this bit is the “binary value” or “digital value” of the
register.
If you use a Word block mapping of 50 registers, you are transferring a block of 50 x 16-bit
values. If you use a Bit block mapping of 50 registers, you are only transferring the digital value
of each register - that is 50 x 1 bit values. This is a lot more efficient for a radio message, but bit
mappings are only suitable for discrete or digital I/O. A Bit mapping will convert the 16-bit
register to a single bit, transfer it and store the bit value in the most significant bit of the
destination register.
Note: The maximum block size for each block mapping is 64 registers.