HP Car 3490A manual InputSignalRequirements, InputSignalsandLevels, Data0utputlsolation

SectionIII

C o l u m n 1 0 9 4 7 6 5 4 3 2 1

-_-_ll-

0 v 3 0 1 2 3 0 0

l +

Model34904

3-77.InputSignalRequirements.

3-78. The RemoteControl option permitsremoteselec- tion of the remote mode of operation, and remote

I

I

Numerical Readino

programmingof rangeand function, including Test and optional Sample/Hold.For input signals,the logic HIGH

L *"nn"

F unction

Polarity/Overload

Sample/Hold Mode

Figure3-5. Option021 Printout.

3-70. The Data Flag @rint Command) output signal changesfrom LOW to HIGH at the beginningof a measurement,and returnsto LOW at the completionof a reading cycle. If the instrument is operatingin the autorangemode, DataFlagremainsHIGH until after one readinghas been completed on the correct range.The HIGH to LOW transition constitutes a Print Command signalto a digital recorder.

3-71.InputSignalsandLevels.

3-12. Three input connectionsare availableat the Data Output connector. The input logic HIGH = + 3.9 V

+1.5V, l00pA max, or an open circuit. The LOW level= + 0.3 V t 0.3 V. 2 mA max. or contactclosureto ground through < 300 A. A HIGH input at the Printer Hold connection causesthe 3490A to stop automatic sampling until the line returns to LOW. A continuous LOW connection at the Hold input preventsautomatic samplingand permits external triggering.WhenHold is LOW, a LOW input level at the External Encodeinput for a mimimum of 240ps initiatesone readingcycle(see. Paragraph3-64).

3-73.Data0utputlsolation.

3-74. Nl output and input lines at the Data Output connector are isolated from the internal (inguard) circuits and from the input terminals.The instrument will maintain all normal- and common-moderejection characteristicswith the Data Output lines properly connected. Outguard ground is isolated from inguard common and from chassis(power line) groundandmay be floated up to 40 V abovechassis.

3 - 75REMOTE.C0NTROL(0ption022) .

3-76. In addition to remote control of range and iunction. the RemoteControl option includesprovision for external triggering.A ProgramFlag output is HIGH during remote program execution, and the Data Flag rrulput is HIGH during a measurementse,quenceA.

:natinEconnector.*rp- Part No. 125l-0084 (Amphenol

\-' r:-3036G375) is suppliedwiththe RemoteControl

. tol:on .

level= + 3.9 V r 1.5V, 100pA max., or an open circuit. The LOW level= + 0.3 V t 0.3 V, 2 mA max., or contact closureto ground through <300 O. Figure 26 showsthe binary codingrequiredfor rangeand function programming,as well as the requirementsfor the other input signals.

3-79.0utputSignals.

-3-80.The ProgramFlag output changesfrom LOW to HIGH at the beginningof outguard-to-inguardtransfer of programinformation, and returnsto LOW to indicate the transferis completeand the instrumentis readyfor a measurementThe. Data Flag output changesfrom LOW to HIGH at the beginningof a measurement,and returns to LOW at the completion of a reading cycle. If the instrument is operating in the autorangemode, Data Flag remains at HIGH until one reading has been completed on the correct range. The logic levels for output signalsare as follows: HIGH = + 3.9 V t 1.5 V,

400l,rAmax; LOW= + 0.3 V r 0.3 V, l5 mA max.

3-81. RemoteProgrammingProcedure.

3-82. All program input lines are HIGH unlessforced LOW by an external connection.The Remote Enable line must be held LOW continuously. If it returns to HIGH, rangeand function programcapability revertsto the front panelcontrols.The remote programsequence is shownin Figure3-6.

3-83.'RemoteGontrol0fTestFunction.

3{4. The Test function may be selectedremotely by programming Function A and B HIGH. Test No. 1, Logic Test, is selectedby programmingthe Autorange line HIGH. Tests No. 2 through 7 are selectedby programmingRangelines A, B and C as indicated in Figure 2-6. WhenTest No. I is selected,a minimum of

l0 readingsmust be taken to record all the test data before changingthe program.In TestNo. 3, a minimum of two readingsis requiredto record the turnover error test. For all other tests,only one readingis necessary. Paragaph 3-38 describesthe internal tests. The - 10 V input required for Test No. 6, and the Q signal short required for Test No. 7 may be appliedthroughout the test sequencewithout affectingthe other tests.In Test No. 4, the ratio referencecheck cannot be controlled remotely.

3-85.RemoteControllsolation.

336.All input and output lines at the Remote Input connector are isolated from the internal (inguard) circuits and from the input termina-lsThe. instrument

l a