User manual

Chapter 4 Configuration
Page 61 ©February 2009
4.5.6 Block Read Mapping’s
A Read mapping is a request sent to another 105G to return a block of values. Like the Block
Write mapping it can be triggered by a Real Time clock, Time period or by Host trigger however
the main difference is that the COS Delay is now a Response Timeout as shown below.
In the above example 105G#3 is performing a Block Read Request to 105G#2.
105G#3 will send a block mapping request to 105G#2 who will then send a block mapping from
its I/O registers 52 for a count of 10 to 105G#4 I/O registers 52 – 61. This Block read will be
performed using the real time clock at 10-minute intervals. A response timeout of 5 seconds is
used to indicate that if the Block read values have not been received in 5 seconds then the
Comms Fail bit for this block read mapping will be set.
It is not recommended to have the Response Timeout set to 0 seconds as a Comms fail bit will be
set upon transmission.
If the Response Timeout is greater than the Block mapping time period and radio’s are in a High
traffic or poor radio path then instances could occur that received messages could be from
previous block read mapping’s hence giving incorrect values.
If a need for frequent communications between modules is required then Block Write mappings
would be more suitable.