Tektronix DIO1A Digital Input/Output Module Rev. B User manual

DlOl A

Digital Input/Output Module

The DIOlA Digital Input Output Module provides 32
digital input or output channels at TTL levels. These
channels are grouped into four &bit ports which can be
individually programmed for input or output by soft­ware commands. The inputs are read directly by the host
computer, and the outputs are latched. A power on reset
circuit automatically configures all ports as inputs when
the DIOlA module is powered up.

I/O connections are made to on-card quick disconnect
screw terminal blocks, which accept 16-24 gauge wire
stripped 3/W. In addition to the screw terminals, a
mass termination connector for ribbon cable is provided

on the forward edge of the module.

CAUTION

Always turn off the data acquisition system
power supply before installing or removing
modules. To avoid the possibility of EMI ra­diation, never operate the system with the
top cover open or removed.

module, and is functionally compatible with the older
module. The older DIOl module has hardware switches
for port configuration, while this function is performed
through software for the DIOlA.

User Connections

User connections can be made to either the quick discon­nect terminal blocks at the top of the module, or to the
mass termination connector located at one end of the
board <through the supplied ribbon cable).

Table 1. User-configured Components

Component
Screw Terminals

I/O Connector

t

Designation
Jl-J14

J6

Function
Input/Output

connections
Quick Disconnect

Mass Termination
for Ribbon Cable

The DIOlA module can be installed in any available slot
in any Keithley/DAC Data Acquisition System. How­ever, for best performance any analog modules should
be plugged into the lowest-numbered available slots,
leaving the higher slots for digital modules. To install the
module in a Model 500 or Model 556, remove the top
cover and insert the module in any available slot with the
component side of the module facing the power supply.
To install the module in a Model570 or a Model 575, open
the clamshell cover and insert the module into the option
slot with the component side of the module facing up.
See your data acquisition system manual for details on

opening the system and installing modules.

The DIOlA module can be identified by a Model 575,

5OOA, 5OOP, or 556 mainframe through the use of a Self-ID
resistor which is mounted on the module. The value of
this resistor is measured by the mainframe, and an JD
code is generated from the value. The DIOlA module
uses the same ID code 52 (4530 ohms) as the older DIOl

Documen~umbert 501-916-01 Rev. B
Copyright’ 1989 Keithky Instruments, Inc., Cleveland, OH 44139 [phone]

Screw terminals for making input/output connections
are located on Jl, J2, J3, and J4 across the top edge of the
module board. The channelnumbers (0 to31) are marked
across the top edge of the board and are also shown in
Figure 1.

Two connections each for the module ground (GND) and

+5

volts (+5) are also included on the top edge of the

board. The terminals are intended to be used with 16 to

24

gauge wire stripped 3/W’, and the terminal blocks

can be pulled off of the strip to facilitate connections. A
typical input/output connection for the screw terminals
is shown in Figure 2.

In situations requiring rapid connection and disconnec-

tion of signal lines, J6 can be used as an alternate means of

signal connection. Figure 3 shows the pin diagram for J6,

which is designed for use with a matching optional rib-

DIOl A-l

DIOIA

.Digital Input/Output Module

Mass Termination (J6) Screw Terminals (Jl J4)

I/

/

t

:

:

:

:

:

:

:

:

:

:

1

J6

Terminal Designations

Ground : Pins 1,36

+5 Volts :

PortA :
PortB :
PortC :
PortD :

Figure 1. DIOl AModule Configurafion

Pins 2,35
Pins3-10
Pins11 -18
Pins19-26
Pins 27 - 34

A

Strain Relief

-6 ’
\

Digital Device

p+

::

::

::

. .

::

::

::

::

::

. .

::

ir

CAUTION : Non-isolated lTL

Figure 2. Typical DIOl A Input Connecf ions

Connections only

bon cable available from Keithley. When connecting sig­nals in this manner, the screw terminals should not be
used.

If FMI radiation becomes a problem, use shielded cables
for input and output connections. Connect the shield of
the cable to the baseboard ground ONLY (or one of the
GND terminals of the screw terminal connectors), and
leave the other end of the shield unconnected. Do not use
the shield of the cable as a signal carrying connection.

CAUTION
DIOlA inputs arid outputs are non-isoIated,
meaning that the circuit ground is connected
to power ground. Any circuits connected to
the module must also be referenced to power
ground and must not be floating, or themod­ule may be damaged.

DIOl A-2

Pin 40

G:D CZ31

Ci30 c:29

Ci26 C:27

C:26 CZ25

C:24 0 i5v

Pin 39

Digital Input/Output Module

DIOlA

Input/Output Programming
The 32 digital I/O channels of the DIOlA are grouped

into four ports of 8 channels each. Port A consists of chan­nels 0 to 7, Port B of channels 8 to 15, Port C of channels 16
to 23, and Port D of channels 24 to 31. The function of
each port (and thus, the 8 channels associated with that
port,) can be programmed individually for input or out­put through the use of software commands discussed be­low. The data written to or read from any port can be
handled as a byte of information, in which eight channels
are accessed at one time.

G:D C:23

CL A21

CZO CL9

Left edge
of Module

pin* I PinI

CL8 cE17

C&6

G:D

C&4 C&3

Ck2 &I

C&O

Ci6

GiiD c:7

C:6 CZ5

CZ4

Ci2 c&

0

+5v

c&

ci9

0

+5v

CZ3

Matching 3M Ribbon
Connector Part
No. 3417

TTL Levels and Loading Considerations
When configured for input, each channel of the DIOlA

represents one LS TT’L load to the external circuitry
(2Oj,tA high, 0.4mA low). Logic low should be between 0
volts and 0.5 volts, and logic high should be between 2
volts and 5 volts (standard TTL levels).

When configured as outputs, each channel is capable of
driving a maximum of 60 LS TI’L loads or 15 standard
TTL loads

(maximum

output is 1.2 mA high and 24 mA
low). Logic low will be in the range of 0 volts to 0.5 volts,
and logic high will be between 2.7 volts and 5 volts.

Commands

The DIOlA uses the slot dependent CMDA and CMDB
lines for setup and read/write operations. To select a
port for a read or write operation, or to configure the
ports for input or output, write to CMDA of the appropri­ate slot. In order to write or read data, write to or read

from CMDB for the appropriate slot. See Table 2 for a list
of the slots and memory locations corresponding to the
CMDA and CMDB lines. Figure 4 includes details on the
DIOlA register usage. Memory locations indicated for
these commands assume that the interface card in the
host PC is set for a base address of CPF80. Any other set­ting of the base address will require the appropriate off­set of the supplied command locations.

Figure 3. Connecfor 16 Terminal Configurafion

DIOlA-3

DIOZA

Channels

Digiid

input/Output Module

Select

Gonfigure

and
Port

Reg

setup
CMDA
(Write)

1

32

Input/Output

)

ReadMite Data

CMDB -

(Read/Write)

CMDA (write) Address - Select port, configure port

Must be issued in order to read or write data to a specified port.

b7 c

CMDB (read) Address - Digital input

Read data from specifkl port provided port is contigured as an input port.

CMDB (write) Address - Digital Output

Write data to specSed port provided port is configured as an ougxn port.

D5 D4 D3 D2 Dl DO

‘L

Beleot Port: O-Port 4 Ch O-7

Configure Port A: 1 -Output, O-Input
Contigure Port B : 1 -Output, 0 - Input
Configure Port C : I- Cutput, 0 - Input
Configure Port D: i-Output, O-Input
Enable Configuration Bits : 0 - Cff , 1 -On

1 -Port B. Ch 8-15
O-Port C, Ch16-23
3-Port D, Ch 24-31

Figure 4.

DIOlA-4

DIOIA Block Diagram and Command Register

Digital Input/Output Module

DIOlA

Table2. Locations for Slot Dependent

Commands

Select/Configure

Slot

1

2

Port (CMDA)

XXX80
XXX82

xxx84 XXX85
:
5
6
7
8
9

10

xXx=1

xxx86

xxx88 XXX89

xxx8A
XXX8C

XXX8E

xxx90 x>o(91

xxx92 xxx93

;t 3 digits of IEUN addn

SELECT/CONFIGURE PORT

Location: Slot dependent CMDA write

The CODA write command is used to configure the ports
for input or output, and to select the port that data is to be
written to or read from. Refer to Figure 4 for the follow­ing discussion of the CMDA write data byte.

Digital I/O

OADB)

XXX81
XXX83

XXX87
xxx8B

xxx8D

xxx8F

s,

e.g.

“CFF

operations

NOTE

Upon power up, a random port will be se­lected; therefore, port selection should be ac­complished prior to read or write operation
with CIvlDB.

NOTE

In

some

applications, you may find it useful
to read back the levels previously pro­grammed to a DIOlA port configured for out­put. The value read back will be the last byte
value successfully programmed to the port.
This feature can be implemented using

BASIC’s PEEK command, or the equivalent
memory read function of other languages.
This WAS NOT a capability of the older DIOl
module, and should not be attempted using

the older module.

DIGITAL INPUT/OUTPUT operations
Location: Slot-dependent CMDB read or write
A CMDB read is used to access data from a selected port

when that port is configured as an input port. A CMDB
write is used to write data to the selected port when that
port is configured as an output port. Note that each of the
four ports can be individually programmed as either an
input or output port, as discussed above.

Bits D3 through D7 are used to configure the ports for in­put or output. Bit D7must be set to a logic 1 to enable bits
D3 through D6 to set their appropriate port to an input or
an output port. When bit D7 is set to a logic 0, bits D3
through D6 are ignored. Bits D3 through D6 are used for
PORT A through PORT D, respectively. Setting the ap­propriate bit to a logic 1 sets that port and

all associated

channels, to a digital output. Setting the appropriate bit

to a

logic 0

sets that

port, and

all associated channels, to a

digital input.

NOTE

Upon power up, all ports are set to be digital
inputs.

Bits DO and Dl are used to select a particular port for in­put or output. A value from 0 to 3 will select port A
through port D respectively. Port selection will always
occur with a CMDA write to the DIOlA module, regard­less of the logic value of bit D7.

When a port is configured as an input port, the CMDB
command location is read to access the status of the chan­nels associated with the port. Reading this location will
return an 8 bit binary number, with the DO thru D7 lines
representing the input lines for the selected port as indi­cated in Table 3. Since the inputs are not latched, the data
will reflect the condition of the input channels at the in­stant that the read operation is performed. Note that the
channels being read will depend on the port selected
with the CMDA write command discussed above.

If you need to know the status of a particular channel, a
logical AND instruction can be used to “mask oft?’ the un­necessary bit positions. The mask should contain zeros in
the irrelevant bit positions and logic ones in the bit posi­tions representing the channels in question. The result of
ANDingthemaskwiththeinputdatawillthenbean8bit
binary number with each bit in an irrelevant position

equal to zero. The relevant channels will contain a 1 or a 0
depending on the status of the corresponding bit in the
masked byte (a 1 if the object bit is high, a 0 if the object bit
is low).

DIOlA-5

DIOZA

Dig&z2 Input/Output Module

When reading a DIOlA port with the BASIC PEEK com­mand, the returned value will be a decimal number be-

tween 0 and 255, depending on the status of the input
channels. The status of a particular channel can be deter­mined by ANDing the returned value with the decimal
weighting for that particular channel.
sult is nonkero, the channel is high (logic 1).

EXAMPLE
telmlin~

100 POKE CMDA,O
110 STATUS6 = PEEK(CMDB) AND 64

If the value returned in variable STATUS6 is non-zero,
then channel 6 is high.

If a DIOl A port is configured as output, the value written
to CMDB should be the equivalent of an 8 bit binarynum-

ber, with the status of the 8 bits (1 or 0) representing the
status of the 8 channels of the selected port (high or low).
The channels affected will depend on the selected port, as
outied hi ‘I’abie 3.
into the outputs and will remain unchanged until the
port is written to again, or the port is configured as an in­put port.
the POKE command will be a decimal value in the range
from 0 to 255.

To change the status of one output channel while leaving
the others unchanged, you must know the status of all of
the channels. To accomplish this, a variable in the con­troiiing program could be assigned to the current status
of the port in question (and updated every time the port is

written to), or the output on the port could be read di-

The status of channel 6 on port A is to be de-

- ­Data wr&en to a port will be

From BASIC, the value written to the port using

If the ANDed re-

iatched

rectly from the port using the readback feature (and
stored in a variable).
channels on the particular port is known, the value of the
variable can be changed to correspond to the desired
status of the selected port, and this new value written to
the CMDB location.

In assembly language, this modification can be per­formed by using logical AND and logical OR instruc­tions. When turning a single channel on (high) the vari-

able representing the current port status should should
be ORed with a number equivalent to an 8 bit binary
value with zeros in the bit positions to remain unchanged
and ones in the bit positions to be turned on. When turn­ing a channel off, the port status variable should be
ANDed with an 8 bit binary value with ones in the bit po­sitions to remain unchanged and zeros in the positions to
be turned off

From BASIC, the decimal weight of the bit to be turned on
or off should be added to (off to on) or subtracted from
(on to off) the decimal number that represents the current

er.d- r+-k.r

y”Lr 3LaLUJ. I‘“I GvuAyAc, I.” LULLI uLcul.LLtzL tt vu, IL W”l.uU

be necessary to subtract 8 from the decimal value repre­senting the port status. To turn on channel 8, it would be
necessary to add 128 to the status.

It should be noted that the DIOlA module is command
compatible with the older DIOl module, with the added
programmability of the port configuration versus the
switch selectability of the older module. Programs writ­ten for the older module can be modified for use with the
new module by simply issuing a CMDA WRlTE to con­figure the ports before any input or output is accom­plished.

Cr.” rwrm,rle Lrr Lr.... #.a.,.......-1 A -CL :r-..#...lA

When the current status of all the

DIOlA-6

Table 3.

Bit Position
Weighting
Port A ChanNos. 7 6

Port B Chan Nos. 15 14
Port CChanNos. 23 22
Port D Chan Nos.

Digital I/O Channels and Bit Values

1 D7 1 D6

128 64

31 30

D5 D4
32 16
5 4

13 12
21 20

29 28

I

D2

D3
8 4
3 2

11

10

19 18

27

26