12 Feb
2006
12 Feb
'06
2:22 a.m.
Speaking of current loop interfaces, just exactly how
is data
transmitted? Is it a current pulse train?
Basically, yes. For the digital current loops we're talking about here,
one state is represented by a given current (normally either 20mA or
60mA) flowing round the loop. The other state is no current. So to send
serial data, you turn the current on and off apropriately.
There is also an analogue current loop used for industrial sensors. It
typically uses currents between 4mA and 20mA.
-tony