4.1.5 Four Groups Configuration
In the
FourGroup
configuration, the SMX4030/32 provide four independent multiplexing groups. The groups
function as independent two wire multiplexers. When a channel is selected, any closed channel within the selected
group is opened, than the selected channel is closed. They route Ch1 to Ch8 to the A-bus forming the first group.
Ch9 to Ch16 are routed to the B-bus forming the second group. Ch17 to Ch24 are routed to the C-bus forming the
third group. Ch25 through Ch32 are routed to the D-bus to form the fourth group.
Figure 4-4
.
In the Four Groups configuration, four independent 2-Wire scanners are available.
4.1.6 Thermocouple ColdJunction test Configuration
Setting the 4030 or 4032 to this configuration connects channel 35 (D-Bus) to the primery measurement terminals,
the A-Bus. This provides a measurement path to the optional SMX40T’s active temperature sensor which facilitates
thermocouple Cold Junction temperature measurement. This is required for making accurate thermocouple
measurements. Therefore, while using the SMX40T channel 35 (D-bus) is unavailable as an input. See sectin 4.2.14
for more information.
4.1.7 Disabled Configuration
In the Disabled configuration, all relays, including channel and configuration relays are open. This is the default
configuration, selected on power up, or initialization.
4.2 Scanner Operations
In addition to basic scanner operations such as selecting channels, the SMX4000 series has several built-in
operations, which it more versatile and a lot more capable. These operations include various self-diagnostics
procedures, contact cleaning, and auto scanning and interfacing to external test and measurement instruments.
4.2.1 Trigger Output
The trigger output line,
TrigOut
, maybe enabled or disabled as well as set for a positive or negative polarity using
the
SCANTriggerOutState()
command. Under normal operation, the
TrigOut
line is active for the duration of the
Actuation time. It maybe used to drive or synchronize other test equipment. If set to positive polarity, a positive
edge indicates the selected channel is closed and settled, provided the correct Actuation time is set (use
SCANSetActuationTime()
function to set it). The logic level of TrigOut may be set high or low using the
SCANSetTriggerOut()
function. In the following diagram,
TrigOut
level corresponds to the circuit in figure 3.3.
Signametrics
20
