6.3 FOUR-WIRE TRANSMITTER
A Four-Wire transmitter is connected
so that its positive terminal is
connected to the "I" terminal, and its
negative terminal is connected to the
"COM" terminal. (see fig 4).
Figure 4.
7. CONTROL
The DRA-CSM-1 unit is controlled via
four address lines and one E/T
(Enable/Test) line. The control terminals
(Address and Enable), were designed
to receive control signals from TTL levels
up to 60V so that almost any PLC's DC
output module can be used. (see fig 5).
5
Figure 5.
7.1 ENABLE/TEST
The unit is enabled when "E/T" is in logical "0" (low) state. In a disabled state,
the DRA-CSM-1 outputs no current and reflects a Hi-Z state.
The disabled state of the DRA-CSM-1 multiplexer is used to check the functioning
of all the current inputs. This is performed by simultaneously injecting current pulses
to all 16 channels which cause the functioning channels to flash. This is a quick
and useful means to indicate a blown fuse.
7.2 ADDRESS
The required channel is selected by four address lines.
The operating voltage levels are:
"0" state 0V < Vaddress < 0.4V
"1" state 5V < Vaddress < 60V
