Section 13: Model 3750 multifunction control card
Series 3700A Switch and Control Cards Reference Manual
13-18
3700AS-909-01 Rev. B / December 2011
Power consumption information
You can power off each analog channel if it is not being used to reduce the power required of the
card with
channel.setpowerstate()
. The card has a default static power draw of 3300 mW,
which includes powering the totalizer channels and both analog output channels. If an analog channel
is powered off, it reduces the 3300 mW draw by 820 mW for each channel that is powered off. This
power can then be used for closing relays on other cards within a bank. See Series 3700A Module
Schematics and Connections for more information on power handling information and examples.
The command for controlling power is
channel.setpowerstate(<ch_list>, <state>)
, where
<state>
is either
'channel.ON'
or
'channel.OFF'
.
NOTE
If an analog channel has been turned off, the specified warmup time is required after being turned
back on in order to meet its specified accuracies.
Using match counts
Match counts apply to digital inputs and counter/totalizer channels.
Setting and meeting match counts
Matching allows you to set a state or generate an event when achieving a match, instead of
continually reading the totalizer count. For example, you can set a totalizer count match and the
summary does not change until that match count is met.
For example, we want to know when a totalizer count reaches 50 for the first totalizer in Slot 1 (that is,
Channel 1006). First set the match type for that channel:
channel.setmatchtype('1006', channel.MATCH_EXACT)
Next, program the match count:
channel.setmatch('1006', 50)
Once the match count is met in the totalizer, the
channel.IND_MATCH
bit is set and can be read
using
match_value = channel.getstate('1006')
Because the default setting for the state is for it to latch, the value remains even after the count
moves beyond the match value. To clear it, use:
channel.resetstatelatch('1006', channel.IND_MATCH)
Using match counts to generate an event
A match can cause an event in the system that can then be used to initiate a scan. For example:
-- Define a scan
scan.create("6001:6030")
channel.trigger[1].set('1006', channel.IND_MATCH)
scan.trigger.arm.stimulus = channel.trigger[1].EVENT_ID
-- Start the scan so that it is waiting for the event
scan.background()
Once the count matches, the event triggers and satisfies
arm.stimulus
, which allows the scan to
proceed.
