Philips PM 8956 01, PM 8956A Service and user manual

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PH ILIP

IEEE-488/IEC-625 BUS Interface and RS232-C/V24 BUS Interface for Digital Storage Oscilloscope PM3320A and 2 GHz Digitizing Oscilloscope PM3340 PM8956A/01

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NOTE: The design of this interface is subject to continuous development and improvement. Consequently, this interface may incorporate minor changes in detail from the information contained in this manual.

© N.V. PHILIPS GLOEILAMPENFABRIEKEN-EINDHOVEN-THE NETHERLANDS-1989 Printed in the Netherlands.

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1. INTRODUCTI ION 1-1
1.1 How to use this manual 1-1
2. INSTALLATI ION INSTRUCTIONS 2-1
2.1 Initial inspection 2-1
2.2 Removing the instrument covers 2-3
2.3 Installing the P.C.B.'s and the cables 2-4
2.4 Installing the instrument covers 2-5
2.5 Settings of the interface 2-5
3. OPERATING
AND USER T
INSTRUCTIONS INCLUDING REAL TIME CLOCK, DIGITAL PLOT
EXT
3-1
3.1
3.1.1
3.1.2
3.1.3
Switching-on and power up routine
Switching on
Power-on routine
Default settings after switching-on
3-1
3-1
3-1
3-1
3.2 Additional features 3-2
3.3 Explanation of optional control and option menu structure 3-2
3.4
3.4.1
3.4.2
3.4.3
Digital plot and print modes
Digital plot specification
Digital print specification
Digital plot and print menus
3-20
3-20
3-24
3-26
4. IEEE-488/1 IEC-625 INTERFACE 4-1
4.1 Introduction 4-1
4.2 Structure of the IEEE-488/IEEE-625 bus 4-2
4.3 Bus-line functions 4-4
4.4 The handshake procedure 4-5
4.5 Addressing 4-6
4.6 Address setting 4-7
4.7 SRQ-service request and serial polling 4-11
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4.8 The device status word 4-13
4.9 The device status register and the device status
enable register
4-15
4.10 Data transfer rate and timing specifications 4-17
4.11 Interface function repertoire 4-24
4.12 Electrical specifications 4-24
4.13 Mechanical specifications 4-24
4.14 Specification IEEE-488/IEC-625 interface 4-26
4.15 ISO-code table 4-27
4.16
4.16.1
4.16.2
4.16.3
4.16.4
Multi line messages
GO TO LOCAL command
GROUP EXECUTE TRIGGER command
SELECTIVE DEVICE CLEAR command
DEVICE CLEAR command
4-28
4-28
4-28
4-28
4-29
RS232-C/V2 24 INTERFACE 5-1
5.1 Introduction 5-1
5.2 Definition of the RS232-C interface 5-1
5.3
5.3.1
5.3.2
5.3.3
5.3.4
Data transmission
Synchronization
Character length
Baudrate
Interface transmission modes
5-1
5-2
5-2
5-2
5-2
5-2
5.4 Initial setting 5-3
5.5
5.5.1
5.5.2
Special interface functions
Service request and serial polling
Remote local protocol
5-7
5-7
5-8

Device clear ....................................

Data transfer rate calculation ....................................

RS232-C connector ..... 5-13

II

5.

5.5.3

5.5.4 5.6

5.8 5.9

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6. PROGRAMM ING AN OSCILLOSCOPE 6-1
6.1 Description of possible actions 6-1
6.2
6.2.1
6.2.2
6.2.3
Message protocol for oscilloscopes
Introduction
Separators
Message units
6-2
6-2
6-3
6-4
6.3 Oscilloscope programming 6-6
7. PROGRAMM ING CODES 7-1
7.1
7.1.1
7.1.2
7.1.3
7.1.4
7.1.5
7.1.6
7.1.7
System codes
Separator
Block separator
Unit separator
Call for identity
Wait time delay
Bus learn
Number representation
7-2
7-2
7-3
7-4
7-5
7-5
7-6
7-7
7.2
7.2.1
Super function codes
Super function codes available for this oscilloscope
7-8
7-8
7.3
7.3.1
7.3.2
7.3.3
7.3.4
7.3.5
7.3.6
7.4
Main function codes and low function codes
Main functions available for this oscilloscope
ALL main functions
Main function VERTICAL
Main function HORIZONTAL
Main function MISCELLANEOUS
Main function SPECIAL
Error codes
7-8
7-9
7-10
7-18
7-30
7-50
7-70
8. PROGRAMMI ING EXAMPLES 8-1
8.1 Introduction 8-1
8.2
8.2.1
8.2.2
8.2.3
8.2.4
Driver programs
Driver program HP85 (IEEE)
Driver program IBM (IEEE)
Driver program IBM (serial)
Driver program P2000C (IEEE)
8-1
8-1
8-2
8-3
8-4
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Page

8.3 How to use the driver programs? 8-5
8.4
8.4.1
8.4.2
8.4.3
8.4.4
8.4.5
8.4.6
8.4.7
8.4.8
8.4.9
Programming exercises
Text
Data transfer
Dumping data to a printer (serial printer)
Use of UP/DOWN/NORMAL + SRQ
Front settings
Register savings
Event counting
Plotting register Ø, using a controller
Bus learn
8-7
8-7
8-10
8-10
8-11
8-12
8-13
8-14
8-15
8-14
9. CHARACTER
REAL TIME
ISTICS OF IEEE-488/IEC-625, RS232-C/V24 INTERFACES AND CLOCK 9-1
9.1 IEEE-488/IEC-625 interface 9-1
9.2 RS232-C interface 9-2
9.3 Real time clock 9-3
9.4 Front panel control 9-3
9.5 Text on C.R.T. control 9-3
9.6 Cursor control 9-4
9.7 Digital output 9-4
10. SERVICE IN NF ORMAT ION 10-1
10.1 Blockdiagram and memory map 10-1
10.2 The multiprocessor system 10-7
10.3 Explanation of signal names 10-9
10.4 Circuit description 10-10
10.5
10.5.1
10.5.2
10.5.3
Description of the diagnostic software
Introduction
Softkey selectable diagnostic software
Hardware selectable diagnostic software
10-25
10-25
10-25
10-27
10.6 Service tools 10-28
10.7 Parts list 10-29

IV

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1. INTRODUCTION

This interface is a general purpose bus line interface according to the IEEE-488/IEC-625 and the RS232-C/V24 document by which the oscilloscope can be adapted to make communication possible with other IEEE-/IEC-bus and RS232-C/V24 compatible measuring instruments.

For more detailed information about the bus system refer to the PHILIPS INSTRUMENTATION SYSTEMS REFERENCE MANUAL 9499 997 00411.

For more detailed information about the functioning of the hardware of the interface refer to the SERVICE INFORMATION, chapter 10 of this manual.

1.1 HOW TO USE THIS MANUAL

This handbook has been designed to enable you to use the utmost potential of this option and to answer your questions concerning programming the oscilloscope and how to connect the system to an IEEE controller or to a serial interface.

If you have just received your option, read chapter 2. (INSTALLATION INSTRUCTIONS) before you attempt to operate the instrument. This chapter contains initial installation information and precautions.

Then you can become familiar to the programming of the instrument by reading and following the examples in chapter 8 of the manual.

The best way to feel at ease with the system is to sit down with the programming manual chapter 7 PROGRAMMING CODES, type in the simple driver program (described in section 8.2) and actually key in the commands from chapter 7 or the examples provided in chapter 8.

It won't take long to become familiar with the programming of the oscilloscope and it is well worth the time you invest to obtain a more complete understanding of the "Remote Controlling" of your oscilloscope.

A number of different functions are covered by the term INTERFACE. They cover the most applicable instrumentation interfaces.

Data and communication protocol aspects are slightly described in these chapters.

These descriptions to a large extent are independent of the lower level functions, as these are laid down in the IEC-625 and IEEE- 488 standards or by the V24 and RS232-C data communication standards.

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2. INSTALLATION INSTRUCTIONS

NOTE: Installation should be carried out by qualified personnel only.

2.1 INITIAL INSPECTION

Check the contents of the shipment for completeness and note whether any damage has occured during transport. If the contents are incomplete, or there is damage, a claim should be filed with the carrier immediately, and the PHILIPS Sales or Service organisation should be notified in order to facilitate the repair or replacement of the interface.

The following parts should be included in the shipment:

- 1 plug-in printed circuit board.

  • 1 IEEE-488 connector, fitted on a small P.C.B.
  • 1 RS232-C connector, with a flatcable attached.
  • 1 short 10-wire flatcable with connectors.
  • 1 long 10-wire flatcable with connectors.
  • 1 long 26-wire flatcable with connectors.
  • 2 hexagonal nuts with washers.
  • 1 Instruction manual.

Check that all jumpers (8 pcs) on the plug-in printed circuit board are positioned as indicated in figure 2.1.

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Figure 2.1 Position of the jumpers.

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2.2 REMOVING THE INSTRUMENT COVERS

WARNING: The removal of covers is likely to expose live parts, and also accessible terminals may be live. The instrument shall be disconnected from all voltage sources before any installation during which the instrument will be opened. If afterwards any adjustment, maintenance or repair of the opened instrument under voltage is inevitable, it shall be carried out only by a skilled person who is aware of the hazards involved. Bear in mind that capacitors inside the instrument may still be charged even if the instrument has

- Switch the POWER ON-OFF switch to OFF.

- Disconnect the oscilloscope from the mains supply.

been separated from all voltage sources.

The instrument is protected by three covers: a front protection cover, a top cover and a bottom cover. To facilitate the removal of the instrument's covers, first put the front protection cover in position.

Then proceed as follows:

  • Hinge the carrying handle clear of the front protection cover.
  • Stand the instrument on its protective front cover on a flat surface.
  • Unscrew the two screws A and B present in the left foot and the two screws C and D present in the right foot at the rear panel and remove these feet (see figure 2.2).
  • The top cover and the bottom cover (without carrying handle) can be removed by shifting them backwards and lifting them of the instrument.

Figure 2.2 Removing the rear feet.

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  • Place the oscilloscope on a table in horizontal position with the rear panel towards you.
    • WARNING: Take care of that there are no parts on the table which may damage the printed circuit boards, which are on the bottom side of the instrument.

2.3 INSTALLING THE P.C.B.'S AND THE CABLES

For installation of the printed circuit boards and the cables see also figure 2.3.

Proceed as follows:

  • Remove the bracket from the plug-in board rack.
  • Install the plug-in printed circuit board in slot A7 or A10.
  • Connect the two opposite flatcable connectors of units A6 and A7 or A10 with the short flatcable.
    • NOTE: The first option to be installed in this instrument must always be placed in the OPTION 1 slot (A7). The OPTION 2 slot (A10) may only be used if an option is installed already in the OPTION 1 slot. Depending on the selected slot A7 or A10 jumper X723 (on figure 2.1) must be set in the correct position.
  • Remove the two coverplates from the holes in the rear panel which are reserved for the IEEE-488 and the RS232-C connectors.
  • Remove the two fixation screws of the IEEE-488 connector. The loose metal connector shield should stay on the connector.
  • Install the IEEE-488 connector together with the small P.C.B. by shifting it from the inside of the oscilloscope into the hole reserved for this connector.
  • Fix the connector together with the small P.C.B. by means of the two fixation screws.
  • Install the RS232-C connector together with the flatcable by shifting the flatcable from the outside of the oscilloscope into the hole reserved for this connector.
  • Place the washers on the hexagonal nuts and fix the RS232-C connector with them.
  • Connect the flat cable to the small P.C.B. at the IEEE-488 connector, according to figure 2.3.
  • Install and connect the remaining two long flatcables according to figure 2.3. The cables should be led through the left hole of the transversal partition plate.
  • NOTE: Care should be taken not to damage the flat cables, while installing them.
  • Reinstall the bracket on the plug-in board rack.
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Figure 2.3 Installation of boards and cables.

2.4 INSTALLING THE INSTRUMENT COVERS

  • Reinstall the covers by executing the steps mentioned at section 2.2 "REMOVING THE INSTRUMENT COVERS" in the reversed sequence.
  • NOTE: When reinstalling the top and bottom covers again, take care that the wiring (coaxial cables and flat cables) is not damaged.
  • Connect the peripheral equipment (e.g. a controller) to the IEEE-488 or RS232-C connector on the rear panel.
  • Reconnect the oscilloscope to the mains supply.
  • Turn the instruments on.

2.5 SETTINGS OF THE INTERFACE

Various settings, such as address for IEEE-488 or baud rate for RS232-C, should be done via the softkeys. Therefore, refer to section 3.3 of this manual.

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3. OPERATING INSTRUCTIONS INCLUDING REAL TIME CLOCK, DIGITAL PLOT AND USER TEXT

This chapter outlines the procedures and precautions necessary for operating the additional features, provided by this option. It identifies and briefly describes the functions of the front panel controls and indicators, and explains the practical aspects of operation to the operator. For the use of the explanation structure, please refer to chapter 4.2.1 of the operating manual of the oscilloscope.

3.1 SWITCHING-ON AND POWER UP ROUTINE

3.1.1 Switching on

After the oscilloscope has been connected to the mains (line) voltage in accordance with Section 3.2.1. and 3.2.2. of the operating manual of the oscilloscope it can be switched on with the POWER ON/OFF switch on the front panel. The associated POWER indicator lamp is adjacent to the POWER ON/OFF switch.

Having switched on the oscilloscope, a power-up routine is performed after which the instrument is ready for use.

3.1.2 Power-up routine

When switching on the instrument, note that the internal microprocessor of the oscilloscope automatically starts a test for a number of internal circuits.

If during this test a circuit is found to be faulty, the test stops and this will be indicated as follows:

The instrument fails to operate normally.Some, but not all of the indicator lamps light.

If this occurs, it is recommended to switch off the oscilloscope and switch it on again after a few seconds.

IMPORTANT: If the fault condition persists, contact your local PHILIPS service department.

If the system blocks during operation, it may be due to extremely high static voltages. In this event, an automatical reset of the internal microprocessor system is performed and the operation of the instrument is restored.

3.1.3 Default settings after switching-on

If no back up batteries are installed and the oscilloscope is switched on, an automatic AUTO-SET action is performed.

With back-up batteries installed, the oscilloscope settings at the moment of switching off are restored and the oscilloscope starts up with the same setting.

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3.2 ADDITIONAL FEATURES

The option adds the following features to the oscilloscope:

  • IEEE-488/IEC-625 interface facility.
  • RS232-C/V24 interface facility.
  • Real time clock facility.
  • User text facility.

The text OPTION>, displayed next to softkey 8 in the main DISPLAY menu, appears at the moment that the oscilloscope knows that an option is installed. Depending on the position of the option in the mainframe of the oscilloscope (slot A7 or AlO) the text INTERFACE is displayed in the textfield belonging to softkey 1 or 5 in the DISPLAY OPTION 1 menu.

3.3 EXPLANATION OF OPTIONAL CONTROL AND OPTION MENU STRUCTURE

Option settings can be done via the main DISPLAY menu of the oscilloscope when the text OPTION> is displayed next to softkey 8. Selecting this function by pressing softkey 8, will give the main option menu DISPLAY OPTION 1.

Figure 3.1 Main option menu DISPLAY OPTION 1.

In case this option is installed, and it is the only one in the oscilloscope, the option name for OPTION 1 will be INTERFACE and the option name for OPTION 2 will not be displayed.

Note that options always are installed, starting from slot A7 in the main frame (see chapter 2 INSTALLATION). The next page gives an overview of the menu structure behind the OPTION> softkey.

3-2

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Figure 3.2 Menu structure behind the OPTION softkey.

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After pressing the softkey OPTION in the main DISPLAY menu, menu DISPLAY OPTION 1 is displayed and the possible options can be selected.

1 Optionname> (name of the installed option in slot A7)

With this softkey the option functions can be selected for the option in slot A7.

2 --

3 --

4 --

5 Optionname> (name of the installed option in slot A10)

With this softkey the option functions can be selected for the option in slot AlO.

SINCE THIS MANUAL DEALS WITH THE OPTION PM8956A ONLY INTERFACE FUNCTIONS ARE DISCUSSED.

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If INTERFACE is selected in menu DISPLAY OPTION 1, the OPTION INTERFACE menu is displayed and all the features provided by the option can be activated. The softkey text lines and the softkeys of the oscilloscope are switched to the option. The lowest line of the trace area will now show the current date and time (of the real time clock).

1/5 1 IEEE 488>

/
OPTION
LEEE 488
TALK ONLY 1
LIST ONLY 2
ADDRESSED 3
ENTER > 4
Address:xx
5
6
7
RETURN 8

Selecting IEEE 488> leads to another menu: OPTION IEEE 488, where the interface parameters for IEEE communication can be defined.

1/5 1 1 TALK ONLY

Pressing the softkey TALK ONLY defines the oscilloscope to act as a talker on the bus system. This is indicated by an intensified text TALK ONLY (note that there can only be one talker on the bus system at a given time).

1/5 1 2 LIST ONLY

Pressing the softkey LIST ONLY defines the oscilloscope to act as a listener on the bus system. This is indicated by an intensified text LIST ONLY.

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3-8

1/5 1 3 ADDRESSED

Pressing the softkey ADDRESSED, defines the oscilloscope to act as a talker as well as a listener indicated by an intensified text ADDRESSED.

NOTE: The text ENTER and Address:xx is only visible if the function ADDRESSED is selected.

1/5 1 4 ENTER>

Pressing this softkey selects the ENTER IEEE ADDRESS. Now a new address can be entered by using the numeric keyboard on the front panel of the oscilloscope. Any address between 0 and 31 can be entered and will be displayed in the textline with ? and in the textline Address:xx in the OPTION IEEE 488 menu.

1/5 1 1/5 1/5 1 1/5 1/5 1 CLEAR This function clears the already entered address, which is displayed in the textfield ?. 1/5 1 4 8 EXECUTE Pressing this softkey stores the entered IEEE address and returns the system to the OPTION IEEE488 menu. If EXECUTE is pressed after CLEAR, the previously programmed value remains. 1/5 1 1/5 1

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  • 1/5 1 7 --
  • 1/5 1 8 RETURN

Returns the system to the menu OPTION INTERFACE.

1/5 2 RS232-C>

1/5 2 1 FRAME>

Pressing the softkey FRAME selects the RS232-C FRAME menu where the serial communication parameters like the number of stop bits, the number of data bits and the parity can be defined.

1/5 2 1 STOP BIT

Defines 1 STOP bit in the data frame indicated by an intensified text 1 STOP BIT.

1/5 2 1 2 2 STOP BIT

Defines 2 STOP bits in the data frame indicated by an intensified text 2 STOP BIT.

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1/5 2 1 3 7 DATA BIT Defines 7 DATA bits in the data frame indicated by an intensified text 7 DATA BIT. 1/5 2 1 4 8 DATA BIT Defines 8 DATA bits in the data frame indicated by an intensified text 8 DATA BIT. 1/5 2 1 5 ODD Defines an odd parity (this means an odd number of "ones" in the data part of the frame) indicated by an intensified text ODD. 1/5 2 1 EVEN 6 Defines an even parity (this means an even number of "ones" in the data part of the frame) indicated by an intensified text EVEN. 1/5 2 1 NO Defines NO parity indicated by an intensified text NO. 1/5 2 RETURN 1 8 Pressing this softkey will store the entered frame

Pressing this softkey will store the entered frame format and the system returns to the previous menu OPTION RS232-C.

1/5 2 2 OUTP SPEED>

RS232-C OUTP SPEED

1

2

3

4

6

8

Range:

Baudrate

75 .. 19k2

UP DOWN

RETURN

After selecting OUTP SPEED>, the output baudrate of the serial interface can be defined. The available range for baudrates is: 75, 110, 150, 300, 600, 1200, 2400,

4800, 9600 and 19200 baud.

The actual output speed is displayed in the textfield ?.

1/2 2 2 T

1/5 2 --

3-10

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1/5 2 1/5 2 4 1/5 2 5 UP Pressing this softkey will increase the actual baudrate with one step in the range until the maximum baudrate of 19200 baud is reached. 1/5 2 2 6 DOWN Pressing this softkey will decrease the actual baudrate with one step in the range until the minimum baudrate of 75 baud is reached. --1/5 2 1/5 2 8 RETURN Pressing this softkey, returns the system to the

Pressing this softkey, returns the system to the previous menu OPTION RS232-C.

1/5 2 3 INP SPEED>

RS232-C INP SPEED Range: 1 Baudrate 2 75..19k2 3 New speed: 4 UP 5 DOWN 6 -- 7 RETURN 8

The input baudrate of the serial interface can be defined. The available range for baudrates is:

75, 110, 150, 300, 600, 1200, 2400, 4800, 9600 and 19200 baud.

The actual input speed is displayed in the textfield ?.

1/5 2 3 1
1/5 2 3 2
1/5 2 3 3
1/5 2 3 4
1/5 2 3 5 UP

Pressing this softkey will increase the actual input speed with one step in the range until the maximum baudrate of 19200 baud is reached.

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1/5 2 3 6 DOWN
Pressing this softkey will decrease the actual
input speed with one step in the range until the
minimum baudrate of 75 baud is reached.
1/5 2 3 7
1/5 2 3 8 RETURN
Pressing this softkey, returns the system to the previous menu OPTION RS232-C.
NOTE: The textline SDPISPOSP, displayed in the
menu OPTION RS232-C stands for Stop bits,
Data bits, Parity, Input SPeed and Output
SPeed (see also section 5.4).
28E1K2075 means:
2 Stop bits, 8 Data bits, Even Parity, 1200
baud input speed and 75 baud output speed.
1/5 2 4
1/5 2 5
1/5 2 6
1/5 2 7
1/5 2 8 RETU RN
Pres:
prev:
sing this softkey returns the system to the
ious menu OPTION INTERFACE.
1/5 3
1/5 4
1/5 5 USER TEXT >
OPTI
USER
CURS
CURS
CLEA
U L
UPPE
LOWE
RE
ON
TEXT
OR =>
OUT
OR <=
R LINE
M
CR CONF
CR CONF
CC CONF
CTURN
With function USER TEXT it is possible to
define a text of 80 characters. This text
will be displayed on the bottom text area of
the C.R.T. screen, and is only visible if the
USER TEXT menu is activated.
The user text can be read by the interfaces.
The user text line is split up in two parts
of 40 characters on the bottom text area of
the C.R.T. screen. The actual cursor position
is indicated with an
When the cursor moves over already existing
text, the cursor position is indicated by an
intensified character in the text line. There
are three character types available to
select.
1/5
1/5
1/5
1/5
1/5
1/5
1/5
1/5 2
1/5 2
1/5 2
1/5 2
1/5 2
1/5 2
1/5 2
1/5 2
1/5 3
1/5 4
1/5 3
1/5 4
1/5 5
1/5 2 3
1/5 2 3
1/5 2 3
1/5 2 3
1/5 2 3
1/5 2 6
1/5 2 6
1/5 2 7
1/5 2 6
1/5 2 7
1/5 2 8
1/5 2 8
1/5 3
1/5 4
1/5 4
1/5 5 USER
OPTION
USER TEXT
CURSOR <=
RUB OUT
CURSOR <=
CLEAR LINE
U L M
UPPER CONF
LOWER CONF
MISC CONF
RETURN
1/5 2 3 6 1/5 2 3 7 1/5 2 3 8 1/5 2 3 8 1/5 2 3 8 1/5 2 5 1/5 2 6 1/5 2 7 1/5 2 7 1/5 2 8 RETUR 07100 USER TEXT CURSOR => [] 0/5 4 [] [] 1/5 3 [] [] 0/5 USER TEXT [] 0/5 J [] [] 1/5 4 [] [] 0/5 USER TEXT [] [] 0/5 USER TEXT [] [] 0/5 UL M [] [] 0/5 UL M [] [] 0/7 []

3-12

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The actual available upper case character is displayed in the softkey text field "U".

To select another uppercase character press the AMPL/DIV UP/DOWN control of channel A, on the front panel of the oscilloscope. Pressing the left side of the UP/DOWN control decreases the alfabetic order (A...Z). Pressing the right side increases the order. There is an automatic wrap around from Z -> A and from A -> Z.

L (Lower case characters)

from a -> z.

The actual available lower case character is displayed in the softkey textfield "L". To select another lower case character press the AMPL/DIV UP/DOWN control of channel B on the front panel of the oscilloscope. Pressing the left side of the UP/DOWN control decreases the alfabetic order (a...z). Pressing the right side increases the order. There is an automatic wrap around from z -> a and

M (Miscellaneous characters)

The actual available miscellaneous character is displayed in the softkey textfield "M". To select another miscellaneous character press the TIME/DIV UP/DOWN control on the front panel of the oscilloscope.

The following characters are available:

0 1 2 3 4 5 6 7 8 9
: : < = ' > ? 0 [ ]
^ , { } 1 11 #
Ş % & , ( ) * + , -
/

Pressing the left side of the TIME/DIV UP/DOWN control decreases the position in the range showed above, pressing the right side increases the order. There is a wrap around from / to Ø and Ø to /.

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Figure 3.3 User text (also applicable for PM3340).

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1/5 5 1 CURSOR =>

Every time the CURSOR => softkey is pressed, the cursor position advances with one step in the user text lines until the last position is reached (position 40 in the second text line).

1/5 5 2 RUB OUT

The previously entered character is rubbed out. The cursor moves one position backwards.

1/5 5 3 CURSOR <=

Every time the CURSOR <= softkey is pressed, the cursor position is moved to the left with one step until the first position is reached. (position 0 in the first text line).

1/5 5 4 CLEAR LINE

The totally entered text will be cleared when pressing this key. So all 80 characters.

1/5 5 5 UPPER CONF

Pressing this key stores the character, represented at that moment on the position "U" in the textline at the current cursor position on the C.R.T. screen (uppercase character).

1/5 5 6 LOWER CONF

Pressing this key stores the character, represented at that moment on the position "L" in the textline at the current cursor position on the C.R.T. screen (lowercase character).

1/5 5 7 MISC CONF

Pressing this key stores the character, represented at that moment on the position "M" in the textline at the current cursor position on the C.R.T. screen.

1/5 5 8 RETURN

Returns the system to the previous menu OPTION INTERFACE.

NOTE: When pressing the CONFirm function (U, L or M) the cursor advances one position.

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1/5 6 CALIBRATE>
/
OPTION
CALIBRATE
Last date: 1
2
Current 3
date: 4
CALIBRATE 5
6
7
RETURN 8

The function CALIBRATE offers the possibility to write the calibration date into the backup memory of the oscilloscope, indicating the last calibration and/or service date.

  • 1/5 6 1 --
  • 1/5 6 2 --
  • 1/5 6 3 --
  • 1/5 6 4 ---
  • 1/5 6 5 CALIBRATE

Pressing this key enters the current date in the memory. The last stored date will be changed into the current date.

  • 1/5 6 6
  • 1/5 6 7 --

1/5 6 8 RETURN

Returns the system to the previous menu OPTION INTERFACE.

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1
1
2
2
2
4
5
6
7
8

7 With the CLOCK function it is possible to set the date and the time of the real time clock via the OPTION CLOCK menu.

The display of the TIME and the DATE is a part of the display of register R3 and can be shifted over the screen, using the Y-POSITION control.

1/5 7
              SET TIME>

7 1/5 7 5 --1/5 7 1 6

1/5 7

1/5 7

CLEAR

The already entered time setting is cleared when this softkey is pressed.

Page 30

  • 1/5 7 1 7 --
  • 1/5 7 1 8 RETURN

Pressing this softkey stores the entered time and returns the system to the previous menu OPTION CLOCK.

1/5 7 2 TIME

This softkey defines the display of the TIME on the screen (ON/OFF), indicated by an intensified text TIME. TIME is a toggle function: the TIME is displayed in the lower right corner of the C.R.T. screen, even if no OPTION MENU is selected.

1/5 7 3 --

1/5 7

1/5 7 4 ---

5

1/5 7 5 SET DATE>

Pressing the softkey SET DATE> results in the ENTER DATE menu. Now it is possible to enter the date via the ENTER keyboard on the front. 1 Enter year Enter: year уу month dav 2 month mm like: 3 day dd yy.mm.dd Leap year correction is implemented. 5 CLEAR 6 7 8 EXECUTE 1

1/5 7 5 2
1/5 7 5 3
1/5 7 5 4
1/5 7 5 5
1/5 7 5 6 CLEAR
The already entered date setting is cleared when
this softkey is pressed
1/5 7 5 7
Page 31

1/5 7 5 8 EXECUTE

Pressing this softkey stores the entered date and returns the system to the previous menu OPTION CLOCK.

1/5 7 6 DATE

This softkey defines the display of the DATE on the screen (ON/OFF), indicated by an intensified text DATE. DATE is a toggle-function. The DATE is displayed in the lower right corner of the C.R.T. screen, even if no OPTION menu is selected.

1/5 7 7 --

1/5 7 8 RETURN

Returns the system to the OPTION INTERFACE menu.

1/5 8 RETURN

Returns the system to the DISPLAY OPTION 1 menu.

  • 6 --
  • 7 ---
  • 8 RETURN

Returns the system to the main DISPLAY menu of the oscilloscope.

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3.4 DIGITAL PLOT AND PRINT MODES

The oscilloscope functions are now extended with DIGITAL PLOT and DIGITAL PRINT modes like the REGISTER PLOT, the REGISTER PRINT, the REGISTER AUTO PLOT, the REGISTER AUTO PRINT, the SCREEN PLOT and the SCREEN PRINT mode.

REGISTER PLOT and REGISTER PRINT stands for direct plotting or printing of register contents without the influence of display functions like for example Y-POS, Y-MAGNIFY, X-POS, X-EXPAND, X-MAGNIFY, INVERT or DOTS.

SCREEN PLOT and SCREEN PRINT stands for plotting or printing of register contents including the influence of the above mentioned display functions.

NOTE: 1) To assure a good plotter/printer-oscilloscope initialisation for the serial interface, first switch on the plotter/printer and then the oscilloscope. Also use this way of initialisation when you change the plotter language. (HPGL - PHILIPS and vice versa).

2) When for some reason the interface initialisation went wrong, and the interface is blocked, a message

DIGITAL output activated, but no output on selected interface

is displayed on the screen of the oscilloscope.

In this case:

  • Re-initialise the oscilloscope (switch off/on).
  • Check the cable connections to your plotter.
  • Check the interface parameter settings via the OPTION INTERFACE menu.
  • Check the plotter or printer interface selection via the DIGITAL SELECT menu.

3.4.1 Digital plot specification

3.4.1.1 REGISTER PLOT mode (via the SAVE/PLOT menu)

1: Plotter pens:

Pen 1 is used for the data and text of channel A. Pen 2 is used for the data and text of channel B. Pen 3 is used for texts which are not related to channel A or to channel B. Pen 4 is not used. Pen 5 is used for the graticule, the time and the date.

2: Time and date:

The time and the date are plotted above the upper right corner of the graticule.

Page 33

3: Text:

The FULL text of the selected register is always plotted and is placed below the lowest graticule line. Settings like CHANNEL IDENT, A versus B and INVERT (selected via the DISPLAY menu) are taken into account during the plot.

4: Plot size:

The data plot area is 10 div. (H) x 10 div. (W).

The plot size (including text) can be changed (via menu PLOTTER SETUP) with a multiplication factor. With a factor of 1, each division is 1 cm (H) x 1 cm (W). This factor has a range of 0.5 to 2.0 with a resolution of 0.1. The default Y-POS, Y-MAGNIFY, X-POS, X-EXPAND and X-MAGNIFY are taken into account on the plot-out.

5: Quadrant:

The plot quadrant on the plot medium can be selected via the menu PLOTTER SETUP.

6: Grid:

The grid to be plotted can be selected via the menu PLOTTER SETUP.

7: Plot output direction:

The plot output can be directed (via menu PLOTTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the plot time) or the RS232-C interface.

8: Signal processing:

The signal to be plotted, can be processed before plotting, to increase the plot speed. This means that vertical changes in the signal of about 5 bit will not result in a real plot action. Only if a dot is out of this range, a line is plotted (starting at the last plotted dot) to just before this point, after which the signal processing algorithme starts again. This may introduce some distortion. Signal processing is carried out if SMOOTH (PM3320A) or AVERAGE C=4 (PM3340) is selected. Signal processing is not posssible if A versus B is selected.

9: Dots plot:

Only dots, without dot join, can be plotted. Between every two dots a pen-up and pen-down is given. This plot mode is carried out if DOTS is turned on. This mode is recommended for eye-patterns.

Page 34

3.4.1.2 REGISTER AUTO PLOT mode (via the SAVE/PLOT menu, only if SINGLE shot mode is selected)

1: Plotter pens:

Pen 1 is used for the data and text of channel A. Pen 2 is used for the data and text of channel B. Pen 3 is used for texts which are not related to channel A or to channel B. Pen 4 is not used. Pen 5 is used for the graticule, the time and the date.

2: Time and date:

The time and the date are plotted above the upper right corner of the graticule.

3: Text:

The plotting of FULL text depends on whether the FULL text is selected for display on the C.R.T. screen or not. FULL text is placed below the lowest graticule line. Settings like CHANNEL IDENT, A versus B and INVERT (selected via the DISPLAY menu) are taken into account during the plot.

4: Plot size:

The data plot area is 10 div. (H) x 10 div. (W).

The plot size (including text) can be changed (via menu PLOTTER SETUP) with a multiplication factor. With a factor of 1, each division is 1 cm (H) x 1 cm (W). This factor has a range of 0.5 to 2.0 with a resolution of 0.1. The default Y-POS, Y-MAGNIFY, X-POS, X-EXPAND and X-MAGNIFY are taken into account on the plot-out.

5: Quadrant:

The plot quadrant on the plot medium can be selected via the menu PLOTTER SETUP.

6: Grid:

The grid to be plotted can be selected via the menu PLOTTER SETUP.

7: Plot output direction:

The plot output can be directed (via menu PLOTTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the plot time) or the RS232-C interface.

3-22

Page 35

8: Signal processing:

The signal to be plotted, can be processed before plotting, to increase the plot speed. This means that vertical changes in the signal of about 5 bit will not result in a real plot action. Only if a dot is out of this range, a line is plotted (starting at the last plotted dot) to just before this point, after which the signal processing algorithme starts again. This may introduce some distortion. Signal processing is carried out if SMOOTH (PM3320A) or AVERAGE C=4 (PM3340) is selected, Signal processing is not possible if A versus B is selected.

9: Dots plot:

Only dots, without dot join, can be plotted. Between every two dots a pen-up and pen-down is given. This plot mode is carried out if DOTS is turned on. This mode is recommended for eye-patterns.

3.4.1.3 SCREEN PLOT mode (via the DISPLAY menu)

1: Plotter pens:

Pen 1 is used for the data and text of register RØ. Pen 2 is used for the data and text of register R1. Pen 3 is used for the data and text of register R2. Pen 4 is used for the data and text of register R3. Pen 5 is used for the graticule, the time and the date.

2: Time and date:

The time and the date are plotted above the upper right corner of the graticule.

3: Text:

The plotting of FULL and/or REDUCED text depends on whether the FULL and/or REDUCED text is selected for display on the C.R.T. screen or not.

4: Plot size:

The data plot area is 8 div. (H) x 10 div. (W).

The plot size (including text) can be changed (via menu PLOTTER SETUP) with a multiplication factor. With a factor of 1, each division is 1 cm (H) x 1 cm (W). This factor has a range of 0.5 to 2.0 with a resolution of 0.1.

5: Quadrant:

The plot quadrant on the plot medium can be selected via the menu PLOTTER SETUP.

6: Grid:

The grid to be plotted can be selected via the menu PLOTTER SETUP.

Page 36

7: Plot output direction:

The plot output can be directed (via menu PLOTTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the plot time) or the RS232-C interface.

8: Signal processing:

The signal to be plotted, can be processed before plotting, to increase the plot speed. This means that vertical changes in the signal of about 5 bit will not result in a real plot action. Only if a dot is out of this range, a line is plotted (starting at the last plotted dot) to just before this point, after which the signal processing algorithme starts again. This may introduce some distortion. Signal processing is carried out if SMOOTH (PM3320A) or AVERAGE C=4 (PM3340) is selected. Signal processing is not possible if A versus B is selected.

9: Dots plot:

Only dots, without dot join, can be plotted. Between every two dots a pen-up and pen-down is given. This plot mode is carried out if DOTS is turned on. This mode is recommended for eye-patterns.

3.4.2 Digital print specification

  • 3.4.2.1 REGISTER PRINT mode (via the SAVE/PLOT menu)
    • 1: Time and date:

The time and the date are printed above the upper right corner of the graticule.

2: Text:

The FULL text of the selected register is always printed and is placed below the lowest graticule line. Settings like CHANNEL IDENT, A versus B and INVERT (selected via the DISPLAY menu) are taken into account during the print.

3: Print size:

The data print area is 10 div. (H) x 10 div. (W), which corresponds to 10 x 10 cm approx. This size cannot be changed.

4: Grid:

The grid to be printed can be selected via the menu PRINTER SETUP.

5: Print output direction:

The print output can be directed (via menu PRINTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the print time) or the RS232-C interface.

Page 37

6: Dots print:

Only dots, without dot join, can be printed. This print mode is carried out if DOTS is turned on. This mode is recommended for eve-patterns.

  • 3.4.2.2 REGISTER AUTO PRINT mode (via the SAVE/PLOT menu, only if SINGLE shot mode is selected)
    • 1: Time and date:

The time and the date are printed above the upper right corner of the graticule.

2: Text:

The FULL text of the selected register is always printed and is placed below the lowest graticule line. Settings like CHANNEL IDENT, A versus B and INVERT (selected via the DISPLAY menu) are taken into account during the print.

3: Print size:

The data print area is 10 div. (H) x 10 div. (W), which corresponds to 10 x 10 cm approx. This size cannot be changed.

4: Grid:

The printed grid type can be selected via the menu PRINTER SETUP.

5: Print output direction:

The print output can be directed (via menu PRINTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the print time) or the RS232-C interface.

6: Dots print:

Only dots, without dot join, can be printed. This print mode is carried out if DOTS is turned on. This mode is recommended for eye-patterns.

3.4.2.3 SCREEN PRINT mode (via the DISPLAY menu)

1: Time and date:

The time and the date are printed above the upper right corner of the graticule.

2: Text:

The printing of FULL and/or REDUCED text depends on whether the FULL and/or REDUCED text is selected for display on the C.R.T. screen or not.

3: Print size:

The data print area is 8 div. (H) x 10 div. (W), which corresponds to 8 x 10 cm approx. This size cannot be changed.

Page 38

4: Grid:

The grid to be printed can be selected via the menu PRINTER SETUP.

5: Print output direction:

The print output can be directed (via menu PRINTER SETUP) to either the IEEE interface (which is set automatically to TALK ONLY during the print time) or the RS232-C interface.

6: Dots print:

Only dots, without dot join, can be printed. This print mode is carried out if DOTS is turned on. This mode is recommended for eye-patterns.

  • 3.4.3 Digital plot and print menus
  • 3.4.3.1 DIGITAL SELECT menu (see figure 3.4)

This menu can be selected via the SAVE/PLOT menu of the oscilloscope.

Via this menu tree it is possible to select the required plotter or printer, plot or print direction and plot size.

- Press pushbutton SAVE/PLOT, this results in the display of the SAVE/PLOT menu.

8 SELECT>
/
PLOT
SELECT
R0
R1
R2
R3
1
2
3
4
ANALOG
DIGITAL

RELURN
> 5 6 7 8

If SELECT is selected, the PLOT SELECT menu, which now is extended with the function DIGITAL>, is displayed. DIGITAL> can now be selected after which a number of digital plot or print settings can be done.

ANALOG> as described in the operating manual of the oscilloscope, remains possible.

Page 39

8 6 DIGITAL>

/
DIGITAL
SELECT
PLOTTERS >
PRINTERS > 2
3
4
PLOT PRINT 5
6
RETURN

If DIGITAL is selected, the DIGITAL SELECT menu is displayed and the plotter or printer type to be used can be selected.

8 6 1 PLOTTERS>

The DIGITAL PLOTTERS menu is displayed and different plotter types can now be selected.

PM8153/1 8 6 1 8 6 1 2 PM8153/6 8 6 3 PM8154 (only PHILIPS language, no HPGL) PM8155 (use HPGL only) 8 6 4 8 6 5 HP7475A 8 6 1 6 HP7550

Page 40

6 1 1-6

operating the DOWN pushbutton.

Page 41

A selection can be made between the IEEE and the RS232 interface as digital plotter output interface. The interface parameters for serial plotting have to be set accordingly via the OPTION INTERFACE menu.

8 6 1 1-6 8 RETURN

After pushing softkey RETURN, the DIGITAL PLOTTERS menu is displayed again.

  • 8 6 1 7 --
  • 8 6 1 8 RETURN

After pushing softkey RETURN, the DIGITAL SELECT menu is displayed again.

8 6 2 PRINTERS>

DIGITAL
PRINTERS
FX 80 >
HP 2225 >



RETURN
4
5
6
7
8

The DIGITAL PRINTERS menu is displayed and different printer types can now be selected.

  • 8 6 2 1 FX 80 8 6 2 2 HP 2225
  • NOTE : For the FX80 printer are several IEEE interfaces available. Only the interface type 8165 has the capability for the LISTEN ONLY mode. Therefore only FX80 printers, equipped with the 8165 interface, can be used with this oscilloscope.
Page 42

8

6 2 1-2

After pushing one of the two printer select softkeys in the DIGITAL PRINTERS menu, the PRINTER SETUP menu is displayed.

8 6 2 1-2 2 6 1-2 3 GRID 01 8 1-2 4 GRID 2 NO A selection can be made between three grid types or NO grid. Grid 0 is a complete grid, consisting of border lines and vertical and horizontal grid lines. Grid 1 is a grid of border lines and centre vertical and horizontal grid lines. Grid 2 is a grid of only border lines. The selected grid type is displayed intensified. 8 2 1-2 5 6 8 6 1-2 6 8 6 1-2 7 IEEE RS232 A selection can be made between the IEEE and the RS232 interface as digital printer output interface. The interface parameters for serial printing have to be set accordingly via the OPTION INTERFACE menu. 1-2 8 RETURN After pushing softkey RETURN, the DIGITAL PRINTERS menu is displayed again. 8 6 2 3 8 2

Page 43
8 6 2 5
8 6 2 6
8 6 2 7
8 6 2 8 RETURN
After pushing softkey RETURN, the DIGITAL SELECT menu is displayed again.
8 6 3
8 6 4
8 6 5 PLO f PRINT
A se
This
plot
The
election can be made between plotting or printing.
s selection also determines if in the actual
t/print menus PLOT or PRINT appears.
selected option is displayed intensified.
8 6 6
8 6 7
8 6 8 RET JRN
Aft
dis
er pushing softkey RETURN, the PLOT SELECT menu is played again.
8 7
8 8 RETU URN
List a false DETUDY the CAVE DIOT monu is

After pushing softkey RETURN, the SAVE/PLOT menu is displayed again.

Page 44
3.4.3.2 PLOT DIGITAL menu (see figure 3.4)

The REGISTER PLOT function can be selected via the SAVE/PLOT menu, if PLOT was selected before in the DIGITAL SELECT menu:

- Press pushbutton SAVE/PLOT, this results in the display of the SAVE/PLOT menu, which now is extended with the function DIGITAL>.

ANALOG> as described in the operating manual of the oscilloscope, is still possible.

6 DIGITAL>

  • 6 1 --
  • 6 2 ---
  • 6 3 --
  • 6 4 --
  • 6 5 --
  • 6 6 ---
  • 67
  • 6 8 STOP

A PLOT action can be interrupted by pushing softkey STOP. The SAVE/PLOT menu is then displayed again. During a plot action, it is not possible to switch to another softkey menu or to change any other function of the oscilloscope.

3-32

Page 45

3.4.3.3 AUTO PLOT DIGITAL menu (see figure 3.4)

The REGISTER AUTO PLOT function can be selected via the SAVE/PLOT menu, if PLOT was selected before in the DIGITAL SELECT menu:

  • Press pushbutton SAVE/PLOT, this results in the display of the SAVE/PLOT menu.
  • 7 AUTO PLOT>
PLOT
AUTOMATIC


ANALOG >
DIGITAL >

REIURN
5
6
7
8

REGISTER AUTO PLOT is only selectable in the SINGLE-shot mode. (The text AUTO PLOT is not visible in an other horizontal mode).

In this mode, the contents of register RØ is automatically plotted each time that the memory contents is refreshed after a valid trigger signal.

If AUTO PLOT is selected, the PLOT AUTOMATIC menu, which now is extended with the function DIGITAL>, is displayed.

ANALOG> as described in the operating manual of the oscilloscope, remains possible.

7 6 DIGITAL>
/
T
AUTO PLOT
DIGITAL
1
2
3
4
PLOT RØ
5
6
7
STOP 8

After selecting DIGITAL, the AUTO PLOT DIGITAL menu is displayed and the contents of register RØ is plotted. The plot size, the plot quadrant, the grid type and the plotter interface can be selected via the SELECT function of the SAVE/PLOT menu . During the PLOT action, the AUTO PLOT

DIGITAL menu is displayed and a message

* * PLOTTER ACTIVE * Changes are possible after plotter has stopped.

is displayed.

At the end of the DIGITAL AUTO PLOT action, menu PLOT AUTOMATIC is displayed again, and the instrument waits for another single shot acquisition to be plotted.

7 6 1 ---7 6 2 ---7 6 3 ---

Page 46

7 6 4 -- 7 6 5 -- 7 6 6 -- 7 6 7 -- 7 6 8 STOP

A PLOT action can be interrupted by pushing softkey STOP. The PLOT AUTOMATIC menu is then displayed again. During a plot action it is not possible to switch to an other softkey menu or to change any other function of the oscilloscope.

Page 47

3.4.3.4 PLOT DIGITAL menu (see figure 3.5)

The SCREEN PLOT function can be selected via the DISPLAY menu if PLOT was been selected before in the DIGITAL SELECT menu:

  • Press pushbutton DISPLAY, this results in the display of the DISPLAY menu.
  • Press softkey POS Rn, this results in the display of the DISPLAY Rn POSITION menu.
  • Press softkey PLOT>, this results in the display of the DISPLAY PLOT menu, which is now extended with the function DIGITAL>.

ANALOG> as described in the operating manual of the oscilloscope, remains possible.

6 DIGITAL>

6

6

6

6 6

8

STOP

After selecting DIGITAL, a copy of the screen is made on a digital plotter. During the PLOT action, the PLOT DIGITAL menu is displayed and a message

* * PLOTTER ACTIVE *

is displayed.

The settings made with the Y-POSITION control, the X-POSITION control and the X-EXPAND control remain.

At the end of the DIGITAL SCREEN PLOT action the menu DISPLAY PLOT is displayed again.

A PLOT action can be interrupted by pushing softkey STOP. The DISPLAY PLOT menu is then displayed again.

Page 48
3.4.3.5 PRINT DIGITAL menu (see figure 3.4)

The REGISTER PRINT function can be selected via the SAVE/PLOT menu, if PRINT was selected before in the DIGITAL SELECT menu:

- Press pushbutton SAVE/PLOT, this results in the display of the SAVE/PLOT menu, which now is extended with the function DIGITAL>.

ANALOG> as described in the operating manual of the oscilloscope, is still possible.

6 DIGITAL>

  • 6 1 ---
  • 6 2 --
  • 6 3 --
  • 6 4 ---
  • 0 4
  • 6 5 --
  • 6 6 ---
  • 6 7 -
  • 6 8 STOP

A PRINT action can be interrupted by pushing softkey STOP. The SAVE/PLOT menu is then displayed again. During a print action, it is not possible to switch to another softkey menu or to change any other function of the oscilloscope.

Page 49

3.4.3.6 AUTO PRINT DIGITAL menu (see figure 3.4)

The REGISTER AUTO PRINT function can be selected via the SAVE/PLOT menu, if PRINT was selected before in the DIGITAL SELECT menu:

  • Press pushbutton SAVE/PLOT, this results in the display of the SAVE/PLOT menu.
  • 7 AUTO PLOT>
/
PLOT
AUTOMATIC
2
3
4
ANALOG > 5
DIGITAL > 6
7
RETURN 8

REGISTER AUTO PRINT is only selectable in the SINGLE-shot mode. (The text AUTO PLOT is not visible in an other horizontal mode).

In this mode, the contents of register RØ is automatically printed each time that the memory contents is refreshed after a valid trigger signal.

If AUTO PRINT is selected, the PLOT AUTOMATIC menu, which now is extended with the function DIGITAL>, is displayed.

ANALOG> as described in the operating manual of the oscilloscope, remains possible.

7 6 DIGITAL>

/
AUTO PRINT
DIGITAL
1
2
3
4
PRINT RØ
5
6
7
STOP 8

After selecting DIGITAL, the AUTO PRINT DIGITAL menu is displayed and the contents of register RØ is printed. The grid type and the printer interface can

be selected via the SELECT function of the SAVE/PLOT menu .

During the PRINT action, the AUTO PRINT DIGITAL menu is displayed and a message

* * PRINTER ACTIVE * Changes are possible after printer has stopped.

is displayed.

At the end of the DIGITAL AUTO PRINT action, menu PLOT AUTOMATIC is displayed again, and the instrument waits for another single shot acquisition to be printed.

7 6 1 ---7 6 2 ---7 6 3 ---

Page 50

--STOP

A PRINT action can be interrupted by pushing softkey STOP. The PLOT AUTOMATIC menu is then displayed again. During a print action it is not possible to switch to an other softkey menu or to change any other function of the oscilloscope.

Page 51

3.4.3.7 PRINT DIGITAL menu (see figure 3.5)

The SCREEN PRINT function can be selected via the DISPLAY menu if PRINT was selected before in the DIGITAL SELECT menu:

  • Press pushbutton DISPLAY, this results in the display of the DISPLAY menu.
  • Press softkey POS Rn, this results in the display of the DISPLAY Rn POSITION menu.
  • Press softkey PLOT>, this results in the display of the DISPLAY PLOT menu, which is now extended with the function DIGITAL>.

ANALOG> as described in the operating manual of the oscilloscope, remains possible.

6 DIGITAL>

A PRINT action can be interrupted by pushing softkey STOP. The DISPLAY PLOT menu is then displayed again.

Page 52

Page 53

If PRINT is selcted in the DIGITAL SELECT menu (see figure 3.4), then the PLOT DIGITAL menu is called PRINT DIGITAL.

Figure 3.5 Extended display menu structure.

Page 54

Page 55

4. IEEE-488/IEC-625 BUS INTERFACE

4.1 INTRODUCTION

The IEC-bus interface is designed for interconnecting several instruments, programmable or non-programmable, to form a measuring system. International agreements on such a system (using byte serial, bit parallel operation) are defined in IEC Publication 625-1.

To simplify cabling and to allow for extension, the interface is organized as a bus-line system. All instruments are interconnected via a common set of 16 lines.

As the bus-line is common to all instruments, to communicate effectively the problems of interfacing have to be solved within the instruments themselves; i.e. they must be designed with inbuilt IECbus facilities. This enables the user to select the most suitable instruments for his system, regardless of make, knowing that interfacing is not a major problem.

These IEC-bus facilities to be described are the functional, electrical and mechanical requirements of instruments designed for connection to the interface, as defined in IEC Publication 625.

Major characteristics

  • Instruments can be of various manufacture.
  • Different data rates can be adapted.
  • Asynchronous data transfer (up to 1 Mbyte/s) is possible without a controller.
  • System flexibility allows rapid interchange of simple and highly complex equipment set-ups.
  • No cabling problems.

Variants

One other standard conforms to the IEC 625-standard in all respects except for the type of interface connector used (see Section 4.12 Mechanical specifications). This variant is the American standard LEEE-488, sometimes referred to as:

HP-IB HP Interface Bus.

GPIB General-Purpose Interface Bus.

Page 56

4.2. STRUCTURE OF THE IEEE-488/IEC-625 BUS

IEC-bus compatible instruments:

To satisfy the necessary requirements, interface functions are built into the instrument as active circuits. These circuits are dependent on the role of the instrument in the system and are additional to thenormal device functions for which the instrument is primarily designed.

Basically, in any communication link there are:

Listeners

Devices addressed to receive data. More than one listener device can be active on the bus interface at a given time.

Talkers

Devices addressed to send data. Only one talker device can be active on the interface at a given time.

Controllers

Instruments for addressing devices as talkers and listeners, also for sending special commands and control signals. In addition to its control function, a controller must have a talk function and, generally, a listen function.

The data byte transfer control, or "handshake" functions ensure that valid data is offered by the talker, that all listeners are ready to accept it, and also verifies that they have accepted it. The IEC interface includes other functions in addition to the above mentioned listen, talk and control functions.

NOTE: The terms, listener, talker and controller refer to selectable functions and any one device may be capable of being programmed to perform one or more of these functions, as shown in Fig. 4.1. For example, a device with a listener function is able to listen and is termed "listener" when addressed as a listener.

4-2

Page 57

Figure. 4.1 Bus structure and interface capabilities.

Page 58
4.3 BUS-LINE FUNCTIONS

The 16 bus-lines are divided into three functional groups:

8 data lines from the data-bus for multiline messages. 3 lines are used for data-byte transfer control (handshake lines). 5 lines are used for interface management.

The data-bus

The 8 bus-lines allocated for input/output data (DIO 1...8) are used for:

  • Measuring data
  • Programming instructions
  • Status bytes
  • Addresses
  • Interface commands

A data byte consists of 8 parallel data bits. Where more information is needed, a complete message may comprise several data bytes in series. The maximum rate of data transfer over this two-directional asynchronous bus-system is 1 Mbyte per second.

The handshake-bus

These 3 lines control the exchange of data bytes between devices. The lines are briefly defined as:

DAV DATA VALID (controlled by the source)

NRFD NOT READY FOR DATA (controlled by the acceptor)

NDAC NOT DATA ACCEPTED (controlled by the acceptor)

These handshake lines are activated to provide the necessary control whenever data bytes are sent over the 8 data-bus lines. They ensure that a source (generally a talker) regulates its speed to that of the slowest acceptor (generally a listener). During the transfer of a byte, the source handshake function in the interface section of a talker is active, and the acceptor handshake functions of listeners are also active.

The interface management-bus

The five lines of this group each have a specific control function between the controller and the other instruments in the system. Briefly the functions are as follows:

REN REMOTE ENABLE

A system controller facility to enable instruments to be switched between local (front panel) control and remote control.

ATN ATTENTION

A controller facility to select either interface messages or device-dependent messages.

4-4

Page 59

IFC INTERFACE CLEAR

A system controller facility to set the interface in a predefined state or to take over control in a multiple controller system.

SRQ SERVICE REQUEST

A device function to ask for attention from the controller.

EOI END OR IDENTIFY

Used by the talker to indicate the end of a multiple-byte transfer if ATN=0, or used by a controller to obtainresponse for parallel polling with ATN=1 (Identify message IDY=1).

4.4 THE HANDSHAKE PROCEDURE

The handshake procedure ensures the correct exchange of data-bytes between devices. It is the first level of the data transfer.

DAV DAta Valid (controlled by the source)

When DAV=LOW, this indicates that a message on the data-bus is correct and suitable for acceptance.

NRFD Not Ready For Data (controlled by the acceptors)

NRFD=high indicates that all instruments are ready to accept a new data-byte.

NDAC Not Data ACcepted

(controlled by the acceptors)

NDAC=high indicates that all listeners have acceptedthe databyte.

The handshake procedure is best explained by using an example of an addressed talker transferring data to a number of listeners.

Figure 4.2 Handshake procedure.

Page 60

To ensure that the NRFD line is only high when all listeners are ready for data, the individual NRFD lines of each interface are connected as a so called wired-OR configuration; i.e. all instruments programmed as listeners have to signal "high" outputs before this line becomes high; this is also valid for the NDAC line.

The procedure is as follows:

  • At the start of a handshake cycle, the DAV line is at high level thus indicating that the data is not valid. The NRFD and NDAC lines are "low" which means that the listeners are not ready to accept new data.
  • A talker may apply the first data-byte to the data-bus even when DAV is still "high" and if the NRFD line is still "low".
  • When all listeners are ready to receive data, e.g. circuits are settled or previous data has been processed, a ready for data message (NRFD = "high") is given.
  • After a short stabilizing time, the talker responds with a DAV "low", which indicates that data is valid to accept.
  • The listeners react by setting NRFD "low" again and then read the data-byte.
  • As soon as the data has been accepted, each listener makes its NDAC output "high", which results in the NDAC line going "high" when all the listeners have accepted data.
  • The talker then responds with a DAV "high", declaring the data no longer valid.
  • In response to DAV "high", all listeners make NDAC "low", which completes the cycle.
4.5 ADDRESSING

For efficient operation, devices must be properly identified at any given time as either a data source (talker) or a data acceptor (listener). Each device is therefore given a coded address as a means of recognition by the active controller. An address consists of 7 bits.

DIO lines 8 7 6 5 4 3 2 1
Address bits
Talk address
Listen address
x
x
x
Ъ7
1
0
Ъ6
О
1
b5 b4
— Dev
b3
ice a
b2
ddres
b1
s⊥

The address of a device is determined by the position of the five address switches that select b5 to b1 (see ISO-code table, section 4.14 of this chapter). Switches b5 to b1 may not all be switched to 1 (address 31) because it means unlisten. It should also be noted that not all addresses are available, as some are already allocated to controllers. A controller addresses a particular instrument by placing the address code of that instrument on the 8 data lines and, at the same time, making ATN "true" (ATN=1). All devices on the bus compare the address code with their own address by using the message decoding function (part of the IEC interface in the device). The device having the same address as that on the data-bus performs the function of talker or listener, as defined by the address bits b6 and b7 of the address code. Therefore, for identification purpose it is necessary for instruments to have different addresses.

Page 61

4.6 ADDRESS SETTING

The correct oscilloscope address can be set by performing the following steps through the several menues, starting in main DISPLAY menu of the oscilloscope (see fig. 4.4).

ACTUAL MENU STEP N 0 PRESSING KEY # NEW MENU
DISPLAY
DISPLAY OPTION 1
OPTION INTERFACE
OPTION IEEE 488
OPTION IEEE 488
OPTION IEEE 488
OPTION IEEE 488
1
2
3
4
4
4
5
OPTION>
OPTIONNAME>
IEEE 488>
TALK ONLY
LIST ONLY
ADDRESSED
ENTER
8
1/5
1
2
3
4
DISPLAY OPTION 1
OPTION INTERFACE
OPTION IEEE 488
OPTION IEEE 488
OPTION IEEE 488
OPTION IEEE 488
ENTER IEEE ADDRESS
ENTER IEEE ADDRESS 6 Now it is possible to key-in the desired
address of the device, by entering the
numbers via the numeric keyboard
(2 positions).
CLEAR: Clears the already entered
address.
ENTER IEEE ADDRESS
OPTION IEEE 488
OPTION INTERFACE
DISPLAY OPTION 1
7
8
9
10
RETURN
RETURN
RETURN
RETURN
8
8
8
8
OPTION IEEE 488
OPTION INTERFACE
DISPLAY OPTION 1
DISPLAY

Figure 4.3 Address setting in steps.

At delivery, or after switching-on an instrument without a memory backup battery, the oscilloscope is set to device address Ø8, listen and talk (addressed).

Page 62

Figure 4.4 Address setting.

Page 63

4.7 SRQ-SERVICE REQUEST AND SERIAL POLLING

Any device in a system can use the service request line SRQ to ask for service by the controller, even when the data-bus lines are otherwise occupied. An instrument that is in an error- or alarm-condition may request service by sending the SRQ message.

Furthermore, some device activities may take several seconds and it may not be economical to block the whole system until these activities are completed. By using the SRQ facility, it is possible for the controller to continue with other activities and to interrupt these when the time consuming operation is finished. When the SRQ signal is activated by one of the devices, the controller can interrupt all other activities and attend to the device which is requesting for service. First of all it must detect which device gave the SRQ signal. This is done by means of the serial poll facility. As an alternative to interruption, periodic checking of the SRQ line by the controller program is also possible.

If the service request facility is not implemented, only periodic polling of all devices remains as an alternative.

Serial polling

Up to 14 devices can give service request via the SRQ line, providing they each have a service request facility in their IEC interface. Such a device must also have a talk function with a serial poll facility; its message decoding section must be capable of decoding the bus commands SPE (Serial Poll Enable) and SPD (Serial Poll Disable).

If an instrument is serial polled, it puts its status byte on the databus. In the status byte, DIO7 indicates whether an instrument has asked for service (SRQ=1). The other bits may give additional status information regarding the instrument polled; e.g. alarm, busy, ready.

Basically, the service request and serial polling is as follows:

  • A device requests for service by activating the SRQ line.
  • The controller receives a service request message and starts a serial polling routine by placing the device in the serial poll mode with the SPE bus command. This universal command is received by all devices.
  • The controller then addresses each device in turn as talker.
  • The device addressed as (serial polled) talker responds by setting its status byte on the data-bus.
  • The particular device that has requested for service responds with an RQS "true" message (DI07 low) in its status byte.
  • After the controller has inspected all status bytes, it terminates the serial poll mode with the universal bus command SPD (Serial Poll Disable) and carries out the necessary action for the device(s) that made a service request. Note that when ATN becomes false, the last polled device becomes talker. Therefore, if necessary, the device may be unaddressed as talker by addressing another device as talker or the non
    • standardized interface message UNT (untalk; see ISO code table) may be sent.
Page 64

Service can be requested for many reasons:

  • The oscilloscope is ready after power up.
  • The user request (URQ) pushbutton on the frontpanel of the oscilloscope is operated. The status word is then 64 (decimal).
  • An event has occured in the oscilloscope, e.g. autoset has finished.
  • The device is in an erroneous condition; a programming error or operating error has occurred.
  • The input buffer is full or nearly full. The sending device must stop data transfer to avoid blocking the interface, or to prevent loss of data bytes.
  • New, valid data is available but the devices interface cannot output it; e.g. because it is not addressed as a talker.
Page 65

4.8 THE DEVICE STATUSWORD

The device statusword reflects the status of the interface functions. However, since the interface functions can also be activated by device functions, the interface status may reflect some device condition; e.g. service request. The protocols relating to interface status data are covered by the relevant international standards.

The statusword can be read by programming a serial poll action.

Send UNlisten Send SPE (Serial Poll Enable) Make the oscilloscope TALKER Make controller LISTENER Read STATUS-word Send UNTalk Send SPD (Serial Poll Disable)

It may indicate incorrect process conditions (alarm or error status). See for error codes: section 7.4.

The device dependent bits in the STATUS-word of the oscilloscope specify the reasons for service request and/or reflect the status of the device functions.

The device statusword (8 bits) is built up as follows:

128 64 32 16 8 4 2 1 Decimal value (equivalent)
D7 D6 D5 D4 D3 D2 D1 DO Data bits
EXT RQS AB BS EF3 EF2 EF1 EFO Name

EXT : Extension bit. This bit is not used and is always "Ø".

RQS : Request for service bit. This bit is set if the oscilloscope has generated a service request.

AB : Abnormal bit. This bit is set if an erroneous or alarm condition is detected. The status is specified in the bits EF3 - EFØ.

BS : Busy bit. This bit is set if the oscilloscope is measuring (busy with programmed action).

EF3 - EFØ : Status bits. The status reflected by these bits depends on the status of the AB bit.

If AB=Ø then they are defined as:

  • EF3 : Power up service request. After power up a service request is generated with this bit set.
  • EF2 : Statusword service request. If a non-masked event happens in the oscilloscope a service request is generated with this bit set. See also next section about the device status event register and the device status enable register.

EF1 : Not used.

EFØ : Not used.

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If AB=1 they are defined as:

  • EF3 : Not used.
  • EF2 : Data ready to be transferred. New, valid data is available but the devices interface cannot transfer it; e.g. because it is not addressed as a talker.
  • EF1 : Not used.
  • EFØ : Programming error. The device is in an erroneous condition; a programming error has occurred.

A service request with the Abnormal bit set, will override in a nonreversible way a status with the Abnormal bit cleared.

The following statuswords (decimal equivalent) are most usual: Nothing of interest is happening. URQ key is pressed. A non-masked event has happened. Power up passed successfully. Programming error. 100 There is valid data ready, but it cannot be transferred.

By waiting for a service request after a GROUP EXECUTE TRIGGER command the controller can check when the oscilloscope is ready with that measurement.

Page 67

4.9 THE DEVICE STATUS REGISTER AND THE DEVICE STATUS ENABLE REGISTER

A number of events in the oscilloscope may generate a service request with the AB bit reset and with the EF2 bit set (error code 68). After having read the statusword after such a service request, the DEvice Status Register (DESR) can be read with the DESR? command to detect which event caused the service request. Reading the status will clear all bits.

The device status register (16 bits) is built up as follows:

Least significant byte:

128 64 32 16 8 4 2 1 Decimal valu e (equivalent)
| D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 Data bits
SB7
SB6
SB5 SB4 SB3 SB2 SB1 SBO Status Bit

Most significant byte:

.. 2048 1024 512 256 Decimal value (equivalent)

| D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | Data bits

SB15 SB14 SB13 SB12 SB11 SB10 SB9 SB8 Status Bit

Status bit meaning if set:

  • SBO: Since the last restart of the acquisition at least one acquisition was compared to the reference register (refers to SAVE or STOP on DIFFERENCE action).
  • SB1: Since the last restart of the acquisition at least one acquisition had parts that were found to be outside the envelope contained in the reference register (refers to SAVE or STOP on DIFFERENCE action).
  • SB2: Since the last restart of the acquisition the most recent acquisition had parts that were found to be outside the envelope contained in the reference register (refers to SAVE or STOP on DIFFERENCE action).

SB3: Autoset has finished

SB4: Auto-offset has finished.

SB5: Calibration has finished.

SB6: A mathematical calculation has started.

SB7: A mathematical calculation has finished.

SB8: A cursor measurement has started.

SB9: A cursor measurement has finished.

SB10: A single/multiple shot/scan has started.

SB11: A single/multiple shot/scan has finished.

SB12: Reserved for future expansions.

SB13: Reserved for future expansions.

SB14: Reserved for future expansions.

SB15: Reserved for future expansions.

Page 68

These events can be disabled (masked) by the DEvice Status Enable Register (DESE). By setting the corresponding bit in the DESE register an event will not generate a service request.

After a service request due to an unmasked event (error code 68) further service requests with error code 68 are disabled until the DESR has been read.

To control the DESR and the DESE register the following commands are added:

DESE XXXXX DESE ? DESR ?

68.

These commands are described in chapter 7.

NOTE : Be carefull when using the DESE and DESR facility. Because of the continuous nature of calculations, measurements and the SAVE/STOP ON DIFFERENCE function, you may get again a service request right after you read the DESR. This may cause problems in application programs, which are not set up for this. A good advice may be to disable events before reading the DESR by programming DESE Ø after receiving a service request with error code

Page 69

4.10 DATA TRANSFER RATE AND TIMING SPECIFICATIONS

Determining the data transfer rate of the IEC bus is rather complex and depends upon the handshake timing of the acceptor and the source. In most applications however, the talker and listeners will cause a lot of overhead times, additional to the data transfer times of the handshake. This section only deals with handshake timing. To be able to calculate and to predict the time required to transfer a databyte (dab) over the bus, the handshake process itself has to be examined; the times in this process that are of interest to the transfer rate are to be determined. The handshake process between a source and a single acceptor is shown in fig. 4.5.

A source declares its sent data valid (DAV = low) at the moment that the databyte is stabilized on the DIO-lines and the acceptor is ready to receive a databyte (NRFD = high). At the moment that the DAV message becomes true the acceptor will respond to it and starts the input of the databyte; it will load the byte into its input buffer. At the moment that the input process is terminated, the databyte is accepted. This is indicated on the handshake bus by the NDAC-line becoming high (DAC=1).

The DAC-message only indicates that the databyte is accepted. The DACmessage does not indicate that the acceptor is ready again to accept the next databyte. The receiving device has first to implement the accepted byte before it is able to receive a next character; a certain time may be required for printing the received character or for implementing and executing the command (if the received character is to be regarded as control data).

Furthermore, the DAC-message indicates to the source that it may remove the byte from the databus and can send the next databyte. Upon receipt of this DAC-message, the source declares its data invalid (DAV=0) and removes the data from the bus. The source will start a procedure to pass the next databyte to the bus. After this new databyte has been transferred to the bus, a certain settling time is required to stabilize the signals on the DIO-lines. The source is ready to start a new handshake cycle after this settling time. If the acceptor device had already completed the implementation of the previous databyte at this time and is ready to receive the next databyte (RFD=1), the source will declare its new data valid: the handshake cycle starts again.

Figure 4.5 Data transfer time.

Page 70

In the situation described above the source takes more time to pass and settle the next databyte to the bus than the acceptor requires to implement the previous input databyte.

It is obvious that in this case the data transfer rate is determined by the acceptor as well as by the source. The total transfer time equals the time required for input of the data plus the time required and settle the next data to the bus.

In reverse, if the acceptor device takes more time to implement the data than the source takes to pass and settle the data, the data transfer rate is only determined by the acceptor device. The total transfer time equals the time required for input of data plus the time needed to implement this data. Thus an increase of the source speed will not increase the datatransfer rate at all.

-Trd starts at the moment that the acceptor sets NDAC false.

Figure 4.6 Timing diagram.

Page 71

TIMING SPECIFICATION FOR DATA TRANSFER

Data transfer in DATA TYPE DECIMAL mode:

Source Handshake Oscilloscope ---> Controller

Tac = Controller depending Trd = Controller depending Tlst = < 150 ms Tsc = < 10 us (see figure 4.6)

Example:

DAT ?

Figure 4.7 Source handshake timing.

Data bytes

Figure 4.8 Source handshake timing.

Page 72

Acceptor Handshake Controller ---> Oscilloscope Tac = ≤ 8 us (see figure 4.6) Trd = ≤ 10 us (see figure 4.6) Tlst = Controller depending Tsc = Controller depending

Example:

DAT ....

Figure 4.9 Acceptor handshake timing.

Data bytes

Figure 4.10 Acceptor handshake timing.

Page 73

Data transfer in DATA TYPE BINARY mode:

Source Handshake Oscilloscope ---> Controller

Tac = Controller depending
Trd = Controller depending
Tlst = < 150 ms
Tsc = < 6 us

Example:

DAT ?

Data bytes

Figure 4.12 Source handshake timing.

Page 74
Acceptor HandshakeController ---> OscilloscopeTac = < 3 us (see figure 4.6)</td>Trd = < 6 us (see figure 4.6)</td>Tlst = Controller dependingTsc = Controller depending

Example:

DAT ....

Figure 4.13 Acceptor handshake timing.

Data bytes

Figure 4.14 Acceptor handshake timing.

Page 75

DATA_TYPE DECIMAL mode: (worst case if the controller does not limit the speed)

Example:

The transfer rate = 166 kb/s (worst case excluding the set up time of 150 ms).

Page 76

4.11 INTERFACE FUNCTION REPERTOIRE

Interface
function
Identification code Description
Source handshake
Acceptor handshake
SH1
AH1
Complete capability
Complete capability
- Basic talker
- Serial poll
- Talk only
- Unaddress if MLA
Listener function L3 - Basic listener
- Listen only
- Unaddress if MTA
Service request SR1 Complete capability
Remote local RL2 No local lock out
Device clear DC1 Complete capability
Device trigger DT 1 Complete capability
Parallel poll PPO No capability
Controller CO No capability

4.12 ELECTRICAL SPECIFICATIONS

Signal logic

The signal on the interface bus-lines are standardized in negative logic.

"high" state > 2 V 0 false
"low" state < 0,8 V l true

Open collector driven circuits are used for the BUS signals.

4.13 MECHANICAL SPECIFICATIONS

The mechanical characteristics of the IEC interface are briefly outlined in this section. For more detailed information, refer to IEC Publication 625-1, Section 4 Mechanical Specifations, clauses 25 or 29.

Connectors

The IEC-bus cables are provided with 25-pole connectors, type MIL-C-24308. A plug and receptacle combined design allows cables to be stacked together in piggyback fashion and secured by a locking mechanism.

For the oscilloscope the American variant of the IEC system (the IEEEbus), the 24-pole micro-ribbon, connectors (Amphenol or Cinch) is used. The receptacle type connector is located on the instruments rear side.

4-24

Page 77

Cables

To ensure correct system operation, the cables for the interconnection of instruments must comply with the specification laid down in IEC-625. The cable should contain an overall shield and at least 24 conductors, of which 16 shall be used for signal lines and the balance used for logic ground returns.

Each of the signals: DAV, NRFD, NDAC, EOI, IFC, ATN, REN and SRQ, shall be a twisted pair together with one of the logic ground wires. The maximum capacitance existing between any signal line and all other lines connected to ground shall be 150 pF per meter.

IEC-BUS SIGNAL LINES IEEE-BUS
1 DIO 1 1
2 DIO 2 2
3 DIO 3 3
4 DIO 4 4
14 DIO 5 13
15 DIO 6 14
16 DIO 7 15
17 DIO 8 16
B .7.1 17
5 REN 17
r
150 01 6 EOI )
(
160 03 7 DAV 7
8 NRFD 8
9 TEC 0
0
SPO 10
ATN 니니
12 AIN
13 Shield 12
18 Gnd (REN) - | |||||||||||||||||||||||||||||||||||||
230 010 19 Gnd (EOI) | _ | |||2
20 Gnd (DAV) 18
||_{250} O^{12}|| 21 Gnd (NRFD) 19
013 22 Gnd (NDAC) 20
23 Gnd (IFC) 21
24 Gnd (SRQ) 22
25 Gnd (ATN) 23
MAT 2954 - Gnd Logic 24

Figure 4.15 IEC-625-bus connector.

Figure 4.16 IEEE-488-bus connector.

MAT 2955

Page 78

4-26

4.14 SPECIFICATION IEEE-488/IEC-625 INTERFACE

Type of interface ANSI/IEEE
Std.488-1978
-Connector RFI/EMI shielded Amphenol type 57LE-20240-
7700D35G or similar,
intermating with Amphenol
57FE series receptacles.
-Bus drivers E2 Three-state
(true = 00,8 V;
false = 25 V).
-Interfacing
function reper-
toire
Source handshake SH1 Complete capability.
Acceptor handshake AH1 Complete capability.
Talker Τ5 Basic talker : yes
Serial poll : yes
Talk only : yes
Unaddress if MLA: yes
Listener L3 Basic listener : yes
Listen only : yes
Unaddress if MTA: yes
Service request SR1 Complete capability.
Remote local RL2 No local lock-out.
Parallel poll PPO No capability.
Device clear DC1 Complete capability.
Device trigger DT1 Complete capability.
Controller CO No capability.
-Address 030 Software settable, through softkeys and menu.
Indicator CRT In softkeys area.
Default Address 8 At delivery or after
switching-on without back-
up battery.

-Timing

DATA_TYPE DECIMAL mode Source: T1st < 150 ms Tsc < 6 us Acceptor: Tac < 8 us Trd < 10 us DATA_TYPE BINARY mode Source: T1st < 150 ms Tsc < 6 us Acceptor: Tac < 3 us Trd < 6 us

Page 79

4.15 ISO-CODE TABLE

Č 0 Г - Γ 2 ы Γ 4 2 9 7 -
₽7 + 0 0 0 0 - - -
∔ ∔
8 2
0 C 0 - ~ ~ 0 0 0 - - -
≷> 1 ISO-
7 bit
dec
equiv
ATN = 1 1SO-
7 bit
dec
equiv
ATN = 1 ISO-
7 bit
dec / ATN = 1 ISO-
7 bit
dec / ATN = 1 ISO-
7 bit
dec | A
equiv
VTN = 1 tso- dec A
equiv
= NT ISO- dec ATN = 1 ISO-
7 bit
dec ATN = 1
0 0 NUL 0 DLE 16 SP 32 0 0 4 8 16 64 0 ٩ 80 16 - 96 ď 112
|- ] 000 SOH - GTL DC1 17 ГГО 33 - 49 17 ۲ 65 - σ 81 17
70
26 σ 113
∖∼ 0 0 1 0 ) STX ~ DC2 18 8 ~ 3 50 18 8 99 2 œ 82 18 ٩ 98 114
\ ~ 0 0 1 1 ETX ر S 19 ¥ 35 ю ю 51 19 υ 67 З S 83 19 66 S 115
\◄_ 0 1 0 0 EOT 4 SDC DC4 8 DCL 36 4 4 52 20 ٥ 68 4 84 20 σ 100 116
≜_ 0101 ENQ 2 РРС NAK 21 РРО % 37 5 5 23 21 ш 69 5 85 21 υ 101 117
٨ 0 1 1 0 ACK o SΥN 52 æ 9 9 54 22 ц 20 9 > 86 22 102 > 118
0 1 I BEL ~ ETB 33 33 7 2 55 23 71 7 3 87 23 103 3 119
\ 1 0 BS 8 GET CAN 24 SPE 40 ω 8 56 24 Т 72 8 × 88 24 ء 104 × 120
1 0 0 1 H б тст N
U
U
55 SPD ^ 41 6 57 25 73 б 89 25 105 ~ 121

1 0 1 ( г 10 SUB 56 * 42 10 •• 58 26 ۔
74 10 Ν 6 26 106 Z 122
\ = 101 4 7 ESC 27 + 43 ŧ •• 29 27 ¥ 75 1 91 27 × 107 123
_5
[⊒]
1 1 0 ( 2 FF 12 FS 58 44 12 Y 09 28 76 12 ~ 92 28 - 108 124
\ 1 1 0 1 CB 13 GS 5 1 45 13 11 61 59 Σ 22 13 _ 93 29 Ε 109 125
\₹_ 0 80 14 RS 8 46 14 ^ 62 30 z 78 14 ٢ 94 30 с 110 1 126
\₽ 1 15 SN 31 .~ 47 15 ¢. 63 UNL
UNL
0 62 15 t 95 0 111 L 127
| AA
Ab
]1 } 1 ADDF NUP SSS } 1 }J ONDARY
DRESS
ROUP
}

Figure 4.17 ISO-code table.

Page 80

4-28

4.16 MULTI LINE MESSAGES (WITH ATN TRUE)

4.16.1 GO TO LOCAL command

There are three ways to get the oscilloscope out of the remote situation and these are: hardware reset (power off, power on), and via an IEEE bus command GTL (Go To Local) or by activating the REN line. To get the oscilloscope out of its current remote situation send:

X0000001 (with ATN true)

After executing this command the oscilloscope is listening again to the knobs at the frontpanel.

4.16.2 GROUP EXECUTE TRIGGER command

It is possible for the controller to tell the oscilloscope when to start a measurement by using the IEEE bus GET (Group Execute Trigger) command. This is done by sending:

X0001000 (with ATN true)

Since there are two modes of measurement (recurrent, single) there are two different interpretations possible for the oscilloscope:

Recurrent : no interpretation, measurements are continuous Single : re-arm the single shot mode

For these modes there will be a service request after the measurement is ready. This service request will stay active until the status of the oscilloscope is loaded into the controller. After this, the service request is reset by the oscilloscope and can be enabled by a new GET (Group Execute Trigger) command.

4.16.3 SELECTIVE DEVICE CLEAR command

The oscilloscope is capable of receiving and executing an SDC (Selective Device Clear) command from the IEEE bus. The controller sets the selected oscilloscope in the selective device clear state by sending:

Device listener address followed by:

X0000100 (with ATN true)

On receiving this command the oscilloscope will, execute the following:

  • * Clear the IEEE hardware interface and software work space. Interface settings (e.g. block separator) and local/remote status are not affected.
  • * Place a new predefined frontpanel state.
Page 81

4.16.4 DEVICE CLEAR command

The oscilloscope is capable of receiving and executing a DCL (Device Clear) command from the IEEE bus. The controller sets all the devices in the system in the device clear state by sending:

X0010100 (with ATN true)

On receiving this command the oscilloscope will, execute the following:

  • * Clear the IEEE hardware interface and software work space. Interface settings (e.g. block separator) and local/remote status are not affected.
  • * Place a new predefined frontpanel state.
Page 82

Page 83

5. RS232-C/V24 INTERFACE

5.1 INTRODUCTION

The serial interface described in this section is primarily intended to interconnect measuring instruments with other instruments to form a measuring system. A number of disciplines are already laid down for serial interfaces, but these disciplines mainly relate to interchanges between data terminal equipment (DTE) and data communication equipment (DCE). For measuring systems, the serial interfaces referred to must be regarded as connecting data terminal equipment to another DTE. As a consequence, these former disciplines and procedures are not always valid for measuring systems and modifications may be necessary as outlined in this chapter.

Figure 5.1 Typical configuration in measuring systems.

5.2 DEFINITION OF THE RS232-C INTERFACE

The V24 interface is based on the CCITT-Standard V24,28 giving specified signal characteristics for connecting data terminal equipment (DTE) and data communication equipment (DCE). V24 gives the functional specification of the circuits, whereas V28 specifies the electrical compatibility. The standard ISO 2110 assigns connector pin numbers to the circuits. All these documents are covered by the American Standard EIA-RS232-C except for the interchange circuit identification. The mode of data transfer is digital, using the bit serial, byte serial method, over one signal line with common return.

5.3 DATA TRANSMISSION

For efficient data transfer, the following characteristics must be considered.

5-1

Page 84
5.3.1 Synchronization

To enable correct detection of characteristics received, some synchronization between transmitter and receiver is necessary. This is achieved by adding framing information to the data (ISO 1177). For the oscilloscope asynchronous data transfer is used.

Asynchronous formatting is mostly used for measuring systems; common for low speed applications. It adds framing information bits to each data character. Framing information is one start bit preceeding a data character and one or two stop bits following it.

Figure 5.2 Framing.

Interfaces operating at speeds up to 1200 baud normally use two stop bits; those operating above this speed normally use one stop bit. In the "standby" state, when no characters are ready to be transmitted the transmit line is held in the logical "1" state. In asynchronous transmission mode, the even parity is the default value.

5.3.2 Character length

Different character lengths are possible. In measuring systems, 7 or 8 bit lengths are typical and are often switch-selectable. The character length excludes parity, start and stop bits. Normally, the ISO 7-bit code (ASCII equivalent) is used, the 8th bit being used for the parity. The least significant bit (LSB) is sent first.

5.3.3 Baudrate

The speed of the data transmission is specified in bits/sec by the baud rate, which must be selected to apply both to the transmitter and the receiver. Baudrates in use are:

75, 110, 150, 300, 600, 1200, 2400, 4800, 9600 and 19200 baud (bits/sec).

5.3.4 Interface transmission modes

A serial interface is said to operate in a simplex mode or a duplex mode depending on whether it can handle data transfer in one or both directions.

This interface handles data transfer in both directions; i.e. it can transmit and receive (Full Duplex mode).

Page 85
TRANSMITTER RECEIVER
] ~[
MAT 2760

Figure 5.3 Transmission modes.

Full duplex means that:

  • The interface can handle data transfer in both directions simultaneously.
  • Transmitted data is assumed to be returned via the receive line (echoing).

5.4 INITIAL SETTING

The correct data transmission parameters can be set by performing following steps through the several menues starting in the main DISPLAY menu (see fig. 5.4).

Example: 1200 baud, 8 data bits, 1 stop bit, no parity.

ACTUAL MENU STEP PRESSING KEY# NEW MENU
DISPLAY 1 OPTION> 8 DIGDIAN ODTION 1
DISPLAY OPTION 1 2 OPTIONNAME> 1/5 OPTION INTERFACE
OPTION INTERFACE 3 RS232-C OPTION RS232-C
OPTION RS232-C 4 FRAME 1 RS232-C FRAME
RS232-C FRAME 5 1 STOP BIT 2 RS232-C FRAME
RS232-C FRAME 6 8 DATA BIT 4 RS232-C FRAME
RS232-C FRAME 7 NO RS232-C FRAME
RS232-C EXECUTE 8 EXECUTE 8 OPTION RS232-C
OPTION RS232-C 9 OUTP SPEED> 2 RS232-C OUTP SPEED
RS232-C OUTP SPEED 10 UP/DOWN 5/6 RS232-C OUTP SPEED
ĺ UNTIL 1200 (1K2) ROZOZ O COTT SFEED
RS232-C OUTP SPEED 11 RETURN 8 OPTION RS232-C
OPTION RS232-C 12 INP SPEED> 3 RS232-C INPUT SPEED
RS232-C INPUT SPEED 13 UP/DOWN 5/6 RS232-C INPUT SPEED
UNTIL 1200 (1K2) 5/0 NOZOZ O INTOI SPEED
RS232-C INPUT SPEED 14 RETURN 8 OPTION RS232-C
Parity are displayed
SDPISPOSP
Output Speed
Input Speed
Parity
Data bits
Stop bits
l now in the menu.
18N1 K21K2
1K2 (1200)
1k2 (1200)
N
8
1
)) blop bleb, and the
T
OPTION RS232-C 15 RETURN 8 OPTION INTERFACE
OPTION INTERFACE 16 RETURN 8 DISPLAY OPTION 1
DISPLAY OPTION 1 1/ RETURN 8 DISPLAY
Page 86

Figure 5.4 Initial setting.

Page 87

5.5 SPECIAL INTERFACE FUNCTIONS

This section deals with a number of protocols that are not standarized in V24,28 documents, but are applied to instruments equipped with a serial interface.

5.5.1 Service request and serial polling

The service request and serial poll protocol were originally developped and intended for IEC interfaces, but its application has been extended to serial interfaces. This section deals with the implementation of the protocol for serial interfaces in Philips test and measuring instruments.

Serial interfaces do not provide a dedicated service request interrupt line. This means that the facilities for service request in devices equipped with these interfaces are somewhat restricted.

If a not masked reason for service request exists, the RQS-bit in the status byte indicates that service is required; if the reason to request for service is masked, the RQS-bit is not set. In any case, the reason may be specified in other bits of the status byte. A controller operating with devices via serial interfaces can periodically poll the devices to check whether service is required or not. The controller executes a serial poll by sending the interface message ESC7 (1/B, 3/7) to a device. Upon receipt of such a poll command, the device will respond by transmitting the ASCII equivalent of the status byte.

If the oscilloscope status is LOCAL, an ESC7 should be terminated with an SPR. The oscilloscope will put the status word on the bus immediately after the receipt of the SPR.

If the oscilloscope status is REMOTE, an SPR is not necessary;, the status word will be put on the bus immediately after the receipt of ESC7.

Figure 5.5 Serial poll action.

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5.5.2 Remote local protocol

This protocol was also originally intended for application with IEC interfaces; but extended to serial interfaces. This section deals with the implementation for serial interfaces for Philips test and measuring instruments. The following possibilities exist for devices equipped with a serial interface and provided with a remote local interface function.

Local to Remote

A transfer from the local to the remote state can only be performed by a controller by sending the interface message ESC2 (1/B, 3/2). Upon receipt of this "Go to remote" message, an instrument will unconditionally go into the remote state.

Remote to Local

A transfer from the remote to the local state can be performed either by the controller or by the device in the following ways:

  • # the controller sends: ESC1 (1/B, 3/1) Go to local or ESC3 (1/B, 3/3) Go to local and unlock
  • # the device sends (only if unlocked): return to local (RTL=1)

After power on, the remote local function is always in the local state.

5.5.3 Device clear

Instruments equipped with a serial interface and provided with a device clear function, execute this function on receipt of the interface message ESC4 (1/B, 3/4) i.e. device clear. The device clear function returns the device function to a predetermined state. Interface settings (e.g. block separator) and local/remote status are not affected.

5.5.4 Device trigger

Instruments equipped with a serial interface and provided with a device trigger function, execute this function on receipt of the interface message ESC8 (1/B, 3/8) i.e device trigger. The trigger starts a predetermined device action.

Page 89
Pin
no.
CCIT
V24
circuit
RS232-C
eq.
CCITT-V24 descr.
For DTE-DCE
Cable
connection
DTE DTE
1 101 AA Protective ground ·(
2 103 BA Transmitted data )
3 104 BB Received data )
4 105 CA Request to send
5 106 СВ Ready for sending
(CTS clear to send)
6 107 СС Data set ready
(DSR)
7 102 АВ Signal ground >
8
9
10
11
12
13 X
14
15
16
17
18
19
20 108.2 CD Data terminal
ready (DTR)
21
22
23
24
25

Figure 5.6 Pin and circuit allocation.

Page 90

5.6 DATA TRANSFER RATE CALCULATION (RS232-C):

Transfer-time calculation for decimal data transfer via the serial interface. Example: Transfer of 100 data points in decimal format from the oscilloscope to a controller. Interface set-up Baudrate : 1200 Data bits: 8 Stop bits: 2 Parity : NO Mnemonics (sent by the controller) REG Ø,MSC TRACE,INTF RS232_OUT.Ø,DATA_TYPE DECIMAL, BGN Ø,END 99,CNT 1,DAT ?

Response (from the oscilloscope after receipt of DAT ?)

DAT 100 S***[]S***[]S***[].....S***{}

Worst-case a trace data point has a decimal value of -512 (e.g.), this means that each datapoint transmitted consists of 5 bytes.

Calculation

The total number of transferred bytes is:

Each transferred byte looks like:

There are 11 bits per frame and a total transfer of 508 frames. This means a total transfer time for 100 data points of:

508 * 11 = 5588 bits => 5588/1200 = 4.65 s

In a formula:

Transfertime=(l+databits+stopbits+parity)(5*(number of data points)+9)

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Transfer-time calculation for binary data transfer via the serial interface.

Example: Transfer of 100 data points in binary format from the oscilloscope to a controller.

Interface set-up Baudrate : 1200 Data bits 3: 8
Stop bits: 2 Parity : NO

Mnemonics (sent by the controller)

REG Ø,MSC TRACE,INTF RS232_OUT.Ø,DATA_TYPE BINARY, BGN Ø,END 99,CNT 1,DAT ?

Response (from the oscilloscope after receipt of DAT ?)

DAT 100[]#B<Hn><Ln><Hb><Lb><Hb><Lb><}

Worst-case a trace data point has a decimal value of -512 (e.g.), this means that each data point transmitted consists of 2 bytes.

Calculation

The total number of transferred bytes is:

12 + 100 * 2 = 212 bytes Number of bytes per data point (always 2) Number of data points DAT 100[]#B<Hn><Ln> (total 12 bytes)

Each transferred byte looks like:

FRAME:

There are ll bits per frame and a total transfer of 212 frames. This means a total transfer time for 100 data points of:

212 * 11 = 2332 bits => 2332/1200 = 1.94 s

In a formula:

Transfertime=(l+databits+stopbits+parity)(2*(number of data points)+13)

baudrate

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5-12

5.7 ELECTRICAL SPECIFICATIONS

Bus driver requirements DATA (TXD, RXD) Spacing "0" > 3 V Marking "1" < -3 V CONTROL (RTS, CTS, DSR, DTR) ON > 3 V < -3 V OFF Current output < 10 mA Output (driver) Line voltage (Vo) of output -7 V < Vo < 7 V impedance 300 Ohm Input (terminator) Line voltage (Vi) of input -25 V < Vi < 25 V impedance 3000 < R1 < 7000 Ohm

5.8 MECHANICAL SPECIFICATIONS

For RS232-C interfaces a 25-pole connector is used.

Connector requirements:

  • The instrument is provided with a plug-type connector (male).
  • The cable is provided with with receptacle connectors (female).
  • The number of contact pins on the connector is 25.
  • Locking screws are provided to enable cable mounting.
  • The connector meets the military specification MILC-24308 or equivalent.

Cable requirements:

The cable shall be as short as possible.The cable length may not exceed 15 meters.

However, where a longer cable is required, the total capacitance may not exceed 2500 pF.

- The cable will be a "null modem" cable. A null modem cable implies that the wire links between the pins needed to connect two DTEs are provided within the cable (e.g. pin 2 connected to pin 3 of the other terminal).

Page 93

Figure 5.7 RS232-C connector.

Page 94

Page 95

6.1 DESCRIPTION OF POSSIBLE ACTIONS

The interface is capable to carry out the following actions:

SYSTEM FUNCTIONS:

  • Program a "unit separator" (USP).
  • Program a "block separator" (BSP).
  • Program a "record separator" (SPR).
  • Call for "identity" (IDT).
  • Program a wait time (delay time after a BSP or an SPR) (WTD).

SUPER FUNCTIONS:

Front handling (FRO Ø).

- Transfer of frontpanel settings from oscilloscope to controller. - Transfer of frontpanel settings from controller to oscilloscope.

Register handling (REG Ø, 1, 2 or 3)

  • Transfer of register contents from oscilloscope to controller.
  • Transfer of register contents from controller to oscilloscope.
SERVICE REQUEST:

- The oscilloscope can ask for service and will respond its status word when the controller executes a serial poll.

MULTI-LINE MESSAGES:

  • Do a GROUP EXECUTE TRIGGER
  • Do a GO TO LOCAL
  • Do a SELECTIVE DEVICE CLEAR
  • Do a DEVICE CLEAR
  • Do a SERIAL POLL
    • In all examples the oscilloscope is assumed to be set to device address 8.
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6.2 MESSAGE PROTOCOL FOR OSCILLOSCOPES

6.2.1 Introduction

This section deals with the user friendly messages to sent to an oscilloscope or to receive from an oscilloscope via a controller. The basic purpose of the message structure is to provide a flexible tool for moving instructions and/or data into and out of the oscilloscope.

A message record consists of a sequence of one or more message units.

MESSAGE RECORD

  • A message unit is the smallest possible sequence of characters (or bytes) constituting a related data set, generated, processed or interpreted as a unit.
  • A message block is a sequence of one or more related message units. In practice, the number of characters within a block is restricted.
  • A unit consists of two parts. A header and a body.
  • Header and body are always separated by a space (SRØ).
  • Units can be concatinated in a message.
  • Units are always separated with a so called unit separator (SR1).
  • Messages can be separated (using a block separator SR2 or a record separator SR3).
< HEADER > < BODY > < HI EADER > < BODY >|< HE ADER > | < BODY >|
SP USP SP USP SP SPR
SRØ SR1 SRØ SR1 SRØ SR3
First message unit Seco ond message uni t Thir d message unit

MESSAGE RECORD

NOTE: - Only the last message unit can be a query unit (?).

Message structure

Figure 6.1 Message structure.

6-2

Page 97

A message record is a sequence of one or more message blocks constituting the complete device-message. A message begins when a device starts sending data for the first time following a reset or a previously sent record separator; it ends with the record separator.

6.2.2 Separators

Separators are used to distinguish between the various parts in the message, and to mark the several hierarchical levels. In desceeding order of level they are denoted as SR3, SR2 and SR1, for respectively, the record-, block- and unit- separator.

Following separators are used:

TO SEPARATE A HEADER AND A BODY

IEEE: RS232:
Indicated as: SRØ SRØ
Preferred: space
Hexadecimal representation 20 20
Decimal representation 32 32

TO SEPARATE TWO UNITS (UNIT SEPARATOR)

The unit separator is used within a block to distinguish between related message units. However, it is quite usual that the header of the next unit implies the unit separator.

IEEE: RS232:
Indicated as: SR1 SR1
Preferred: comma , ,
Hexadecimal representation 2C 2C
Decimal presentation 44 44

TO SEPARATE TWO BLOCKS OF UNITS (BLOCK SEPARATOR)

The block delimiter is used within a message to distinguish between message blocks. Also here it is common practice that the header of the next block implies the block separator if a message exclusively consists of blocks that only contain one message unit.

IEEE: RS232:
Indicated as: SR2 SR2
Preferred: linefeed LF LF
Hexadecimal representation ØА ØА
Decimal representation 10 110
TO TERMINATE THE LAST BLOCK TRANSMITTED (RECORD SEPARATOR)

The record separator is used to terminate a message. It indicates that there is no additional information available. In IEEE interfaces the END message is sent (via the ATN and the EOI-lines), concurrent with the NL message on the data bus.

IEEE: KSZ3Z :
Indicated as: SR3 SR3
Preferred: linefeed + END LF + END LF
Hexadecimal representation ØA ØA
Decimal representation 10 10

End activates the EOI interface management line.

Page 98
6.2.3 Message units

HEADER indicating the type or quality of the data following in thebody. They refer in general to the quantity of the data rather then to units.

MAT2767

Figure 6.2 Header.

  • Alpha characters are alpha numerical characters of the columns 4 and 5 of the ISO-code table see fig. 4.17 (only upper case).
  • The header defines which function we want to program in an oscilloscope.

BODY containing the data to be transferred. It may represent different data types.

There are two types of bodies possible:

- a character data body - a numerical data body

CHARACTER DATA BODY

MAT 2768

Figure 6.3 Character data body.

There is no restriction for the length of the body, however it must be fixed per device function.

NUMERICAL DATA BODY

Numerical data can be represented in 3 different ways, depending upon the application:

  • Implicit point notation NR1 - Explicit point notation - NR2
  • Scaled representation NR3

Instruments that are able to implement a certain numerical representation (NR) are also able to implement a lower numbered NR.

6-4

Page 99

Implicit decimal point notation (NR1):

(-32768 < NR1 < 32767)

Figure 6.4 Numerical data body - NRl notation.

Explicit decimal point notation (NR2):

Figure 6.5 Numerical data body - NR2 notation. The number zero can be noted as .Ø (and of course Ø, as NR1)

Scaled representation (NR3):

Figure 6.6 Numerical data body - NR3 notation.

Page 100

Leading zero suppression (except for the exponent) is preferred for all numeric notations.

The body defines in this way the new state in which a function, defined by the previous header will end up.

Example:

Common
Notation
NR1 Common
Notation
NR2 Common
Notation
NR3
238 +0238 32.4 +32.4 5600 +005.6E+03
-1 -0001 -3 -003. 0.02 +020.0E-03
0 +0000 0 +000. -4.2 -004.2E+00
6.3 OSCILLOSCOPE PROGRAMMING

An oscilloscope can be set in the local or in the remote states:

Local state : The operator can control the oscilloscope manually, (REMOTE led off). In this state, the controller is able to switch the oscilloscope to "remote state". Remote state: Only the controller on the bus can control the oscilloscope. (REMOTE led on).

Figure 6.7 Two states of the osciloscope.

In the oscilloscope we can devide the REMOTE state into two different states:

Front handling state : Used for programming a new acquisition setting. Register handling state: Used for programming in stored settings and for data transfer. This function is typical for a digital storage oscilloscope.

The way to enter another state is to ask for that state. However, there are exceptions.

  • IEEE commands like GET, SDC and DCL result in the front handling state when coming from the local state.
  • Coming from the local state, any programming action, not preceeded by a new state request is ending up in the front handling state.
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