7000 Series plug-in interface

Tektronix 7000 series oscilloscope mainframes have one (7912) or two vertical plug-in slots, and zero (7612D), one (7xx3, 7912) or two (7xx4) horizontal plug-in slots.

The interconnect on either slot type is a 76-pin PCB edge connector. The pinout on vertical and horizontal slots is not identical but compatible to the point that vertical plugins can be installed in horizontal slots and vice versa. However, in that case, some functions may be unavailable − for example, trigger signals are only routed to H slots so a timebase in a V slot must be externally triggered.

Looking into the mainframe from the front panel, "A" pins are left of the connector centerline (on the plug-in PCB's component side) and "B" are on the right (on the plugin PCB's solder side). Pins are numbered from 1 at the bottom to 38 on the top. In the following table, (H) indicates signals available in horizontal slots only, (H-A) is horizontal slot A, (H-B) is horizontal slot B, and (V) denotes signals available in vertical slots only.

A side B side Pin Function Function 1 Sweep Gate (H) Delay mode ctl in (H-B) 2 Gate common Delay mode ctl out (H-A) 3 A Sweep (V & H-A) [note 1] B Sweep (V & H-B) [note 1] 4 Line trigger Trigger holdoff (H) 5 Chop drive Aux Swp gate (H) 6 Chop common ALT drive 7 Intensity Limit (H) MF Channel Switch 8 +5 V Sweep inhibit (H) 9 +5 V (lights) Delay gate (H) 10 Single sweep ready (H) X comp inhibit (H) 11 +Signal −Signal 12 Signal Ground Signal Ground 13 +Trigger (V) [note 2] −Trigger (V) [note 2] 14 Lights common Dual beam Aux Y-Axis 15 Single sweep logic Single sweep reset (H) 16 MF Mode Aux Y axis (H) 17 Aux Z axis Aux Z common 18 +15 V −15 V 19 +50 V −50 V 20 +Trigger in (H) −Trigger in (H) 21 +Aux trigger in (H) [note 5] −Aux trigger in (H) [note 5] 22 /EOI [note 6] /SRQ [note 6] 23 /DAV REN 24 /IFC [note 3] /ATN 25 /NDAC /NRFD 26 Logic Common /SND 27 −5.2 V [note 4] 5.1 V [note 4] 28 n.c. n.c. 29 TS10 [note 3] TS9 (DIO8) 30 TS8 (DIO7) TS7 (DIO6) 31 TS6 (DIO5) TS5 (DIO4) 32 TS4 (DIO3) TS3 (DIO2) 33 TS2 (DIO1) TS1 [note 3] 34 n.c. n.c. 35 Force readout Plugin mode [note 7] 36 n.c. n.c. 37 Ch. 1 Col Ch. 1 Row 38 Ch. 2 Col Ch. 2 Row Pin group function legend Plugin power HF signals Readout system signals IEEE-488 bus used in 7A16P, 7A29P, 7B90P, digitizer mainframes; data 1-8 on TS2-TS9 lines

Description of signals Sweep Gate − 0/+5 V, high while sweep is running (beam unblanking), connected to +5 V in amplifier plugins; +Gate Output on mainframe uses Sweep Gate from H slot A when A Gate is selected, and from H slot B when B is selected Delay Mode Control − Output on delaying timebase in horizontal slot A, connected to input on delayed timebase in horizontal slot B. >+3 V disables auto sweep in delayed timebase; 0 V enables independent timebase function. Grounded in amplifier plugins. A/B Sweep − 500 mVp-p, negative-going copy of sweep signal from timebase, not affected by X position control or magnifier; Used for mainframe's Sawtooth Out, additionally fed to V plugins Line Trigger − Approx. 1 VRMS mains-frequency signal from power supply (through transformer) Trigger Holdoff − 0/+5 V, generated by time-base, high during holdoff time of time-base, used in mainframe for ALT sequencing. Chop Drive − 0/+5 V; switches at one-half the rate of the VERTICAL MODE CHOP signal; high level selects channel 2, low level selects channel 1 of a dual-trace plug-in. Aux Sweep Gate − 0/+5 V; pulled high by dual-sweep time-base plug-ins during auxiliary sweep Alt Drive − 0/+5 V; high level will display channel 2 of a dual-trace plug-in. low will display channel 1. Intensity Limit − Switched to ground by timebase in slow sweep speeds (≥100 ms/Div), limits beam intensity to protect the CRT phosphor Mainframe Channel Switch, Mainframe Mode − 0/+5 V logic levels; plug-in output is displayed when MF Channel Switch ≠ MF Mode (XOR) Sweep Inhibit/Sweep Lockout - Mainframe injects current > 1 mA to prevent time base from sweeping. Used for ALT sequencing. Delay Gate − negative-going pulse starting at the end of the delay period, and lasting until the end of the sweep from the delaying timebase. +Gate Output on mainframe uses Delay Gate from H slot B when Delay Gate is selected. Grounded in amplifier plugins. Single sweep ready − 0/+5 V, high when single sweep is ready X comp. inhibit − Connected to ground in amplifiers, switched to ground by timebase set to amplifier (X-Y) mode to enable X-Y delay compensation in scopes with that function (7904 Opt.2, 7104 Opt.2) Signal − Signal output from plugin to mainframe. Differential, 50 Ω per side. 50 mV/Div (differential). Trigger − Copy of signal output from V plugin to mainframe. Differential, 50 Ω per side. 50 mV/Div (differential). Terminated on H slots. Dual Beam Aux Y-Axis − Used in dual beam mainframes (7844), Current-driven input to mainframe allowing vertical separation of two traces with dual timebase plugins. 1 mA/Div sensitivity. Single Sweep Logic − 0/+5 V; high level when time-base is in single sweep mode. Single Sweep Reset − Switched to ground to reset single sweep. Aux Y-Axis − Current-driven input to mainframe allowing vertical separation of two traces with dual timebase plugins. 1 mA/Div sensitivity. Aux Z Axis − Current-driven input to mainframe allowing plugins to modulate beam intensity, e.g. in dual timebase A intensified by B display mode; driven only when plug-in output is displayed (see MF Ch Switch above) Trigger In − Trigger signal input on H plugin, routed from V plugin's trigger output. Differential, 50 Ω per side, 50 mV/Div (differential). Aux Trigger In − Only used by 7B52 GPIB lines − Control signal functions are the same as their IEEE-488 (GPIB) equivalents. Time slot lines 2 to 9 double as IEEE-488 data lines. TS1−TS10 − readout system time slot pulses. Idle 0, active −15 V. Force Readout − Allows plug-in readout information to be displayed regardless of the mainframe mode switch setting when pulled low (<0.5 V). Used by many 7DXX plug-ins. Plugin Mode − 5-level signal providing the mainframe with information about the operating mode of a dual-trace or dual-sweep plugin. Ch1/2 Row/Col − Analog current inputs to the readout system. Ch1 refers to the first channel within the plugin slot in question and is associated with the readout field on top of the screen. Ch2 is the 2nd channel displayed at the bottom. Row/Current signals accept negative currents in 100 μA steps; typically, plugins contain resistors from time slot signal lines to row/current lines.

Notes

[note 1] Output from H plugins, input on V plugins

[note 2] Output from V plugins, unused and terminated 50 Ω to ground in mainframe H slots

[note 3] In programmable mainframes, A24 is pulled high to +3 V, indicating to programmable plug-ins to use TS2-TS9 as GPIB lines and a modified readout logic using only TS1 and TS10, with TS1 being active in time slot 1 as in other mainframes, and TS10 being active in each time slot.

[note 4] Not provided by most mainframes (digitizers only?). 7A16P connects B27 to A9, requires −5.2 V on A27.

[note 5] According to the 11000-series interface manual, many 7k plug-in units ground pin B21 or connect it to pin A21, and The 7D10, 7D11, 7D14, 7S14, and possibly some others have pin A21 grounded.

[note 6] A22 = Busy output from 7D12, 7D15, B22 = /Hold input to 7D12, 7D15; no corresponding mainframe connections known

[note 7] The plug-in mode is supplied to the mainframe either as a resistor connected to ground (with 5% tolerance), or by supplying a DC voltage (with 0.25V tolerance):

Plugin Mode	Resistance	Voltage
CH 1, Delaying, Intensified, Normal	≥30 kΩ	5 V
CH 2, Delayed Sweep	3.9 kΩ	4 V
ADD, Mixed Sweep	620 Ω	2 V
ALT	240 Ω	1 V
Chop	0-47 Ω	0 V

Links

• Tektronix 7000-Series Plug-in to Mainframe Interface Manual (PDF, needs OCR)

• Introduction to the 7000 Series Switching and Logic Circuits (Ken Parker, 1970) (PDF,OCR,1MB)
• Kahrs, Interfacing to the Tektronix 7000 series