SectionIII

 

 

 

Model3490A

M R E

 

 

 

 

Data Lines

 

 

 

 

L D A V

 

 

 

 

H R F D

 

 

 

 

Printerand 3490A

390A and printer

349OAand

3490A and printer

Printer will not

will acceptdata

will not accept data

printerwill

will not accept data

accept data

 

 

acceptdata

 

 

Printerand 34904

34904 andprinter

 

 

Printerand34904

finished

34904 and printer

finished

processingdata

processing

processing

data

processing

 

data

 

data

Figure3-9. TimingDiagram,3490AAddressedto Talk.
outputted in the following format: (Example listing: NDCfXXXXXXE-Y).StatusCodeAlpha*NNormal Operation OL OverloadR Ratio ModeS Sample/HoldModeRS Ratio and Sample/HoldModeFunction Code*AC AC VoltsDC DC VoltsKO KilohmsT Test

*Status and Function are two-character codes. lf only one character is required, a blank spacewill be left so that the total output format will always be the same length.

Polarity

+PositiveInput or PositiveRatio-NegativeInput or NegativeRatio

Data

xX)c()ü Six digits, most significant digit firstEExponentIdentifier Polarity of ExponentYExponent(RangeDigit)C R CarriageReturnLF Line Feed

3-127. Service Request.The 3490A is capable of requesting service on the bus and respondingto serial polling for identification and status.If either mode of operation which specifiesinterrupt with output (M5 or M7) is programmedand 34904 is not programmedto talk, it will pull the ServiceRequest (LSRQ) line LOW after eachreading.

3-128. For serial polling, the controller must pull the Multiple ResponseEnable (MRE) line LOW and send both the Status Poll Enable (SPE) command and the 3490A talk address.The SPE command is octal code 030, binary code 00 011 000. If the 3490A has pulled SRQ LOW, when it receivesSPEand its talk addressit will transmit the ASCII characterxlxxxxxx. The seventh bit beinga "l " signifiesthat the 3490A did request service.The other bits do not convey any information concerningthe status.After it receivesthe StatusPoll Dsable (SPD)command(octal code031, binary code 00 0ll 001), the 3490A will output the readingdata,since it is still addressedto talk. After outputting the data,it will return the Service Request line to HIGH. If it is unaddressedto talk before the SPD commandis sent,it will keep the SRQ line LOW and wait for its talk addres to output or its listen addressto be reprogrammed.It will setSRQ HIGH if it is reprogrammed.

3-129. lf the 34904 is in operatingmode M5 or M7 and receivesthe SPEcommandand its talk addressbeforea readingis completed,it will respondwith the character x0xxxxxx. The seventhbit being a "0" indicatesthat it did not request service, and the other bits have no

significanceconceming status. This code (seventh bit "0") is also transmitted if the 3490A is in any of the

other modesof operation(M0,Ut, M2,M3, M4, or M6) and it receivesthe SPEcommandand its talk address.

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