We have tested differential DS link connections over twisted-pair
cable for immunity against electromagnetic interference according
to the IEC 801-4 standard [10]. The setup passed test
severity level 2, which corresponds to the environment likely to be
found in the control room of an industrial or electrical plant. We
have also attempted to quantify the reliability of DS link systems
using the 1024 node 
grid network by performing long-term error tests.
The 1024 node grid contains a total of 1344 active DS links, about
one third of these link use differential buffers and 2 meter twisted
pair cables. The others are single-ended on-board connections. We
have run the system continuously for over 200 hours without observing
any link errors. This translates to a per-link error rate of better
than 
.