Operator`s manual

Figure 4-9. Single Step operation requires a SCANSetupStep() then SCANStep() command.
4.2.7 Scan List Operations
The Scan List table resides on board the scanner. It contains 192 locations, allowing a scan made up of up to 192
channels. Two DLL functions provide means to write and read to this table. The table contains channel numbers
associated with the scanner channels. The Scanner may have entries with values between 1 and 32, representing the
available channel numbers. An entry of zero forces deselection of all channels. The Scan List table may contain
repetition, or a scan sequence with multiple selection of a single channel. Entries to the table are context sensitive.
The current configuration of the Scanner determines how channels numbers are treated. For instance, an entry of 32
is not reasonable while in FourWire configuration. In this configuration, an entry of 1 (Channel 1) will force
selection of two channels, Ch1 and Ch17.
All Auto Scan operations read the table sequentially, starting at address 0 and ending at 191. It is important to
consider the configuration of the Scanner when setting the table. The table may be written and read any time the
Scanner is not busy. Operations using the Scan List include: SCANAutoScan(), SCANSetupStep(), SCANStep(),
SCANStepCmd() and SCANTrigAutoScan().
When several Scanners are connected to form a larger channel count, the use of a zero entry provides for a scan
made up of channels from multiple Scanners. This requires that all Scanners included in the scan are loaded with
identical table values. The following table shows multiple card scanning operation, assuming all Scanners are in
TwoWire configuration.
Scan Table Entries
Scanner
Number
@0 @1 @2 @3 @4 @5 @6 @7
SMX4032 #0 0 0 8 0 0 0 0 1
SMX4032 #1 3 35 0 18 0 0 0 0
SMX4032#2 0 0 0 0 4 5 6 0
Selected
scanner#, Ch.
#1,
Ch3
#1,
Ch35
#0,
Ch8
#1,
Ch18
#2,
Ch4
#2,
Ch5
#2,
Ch6
#0,
Ch1
Figure 4-10. Contents of the Scan List table control Auto Scan sequence.
Use the SCANSetScanList() function to write to the Scanner hardware a channel value and SCANGetScanList()
to read a value.
4.2.8 Locating Shorted Channel
The SCANGetShortedChannel() function scans all channels, and returns the first channel which is shorted. This
can be used to detect a channel to see if it is the appropriate one, be it at the scanner input connector or at the
optional terminal block. It is particularly useful in locating and identifying channel connection at the application end
of a wiring harness.
4.2.9 Self Cleaning the Relay Contacts
Using the SCANCleanRelays() function, the Scanner can clean each relay contact. It does this using a specially
designed on-board stimulus source along with a series of vibrations. This operation causes deposits of contaminants
such as polymer deposits as well as oxides to be removed. It also solves a common relay problem involving thin
film of insolationg deposits, which accumualte particularly on relays which have not been used for a while. It does
this by pinching through this film using an on-board high voltage souce. Performing this function on a regular basis
will improve the scanning system’s reliability and repeatability,as well as prolong contact life. All relays including
23 Signametrics