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! d i g i t a l ! I N T E R O F F I C E M E M O R A N D U M
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Date: 20-January-82
From: TSG/NCSS
Loc: MR1-2/H22
Ext: HOTLINE 5911
Subj: Use of a Datascope
The Spectron Datascope is a monitoring device which can display all
the data transmitted and received over a physical line. It is
hooked into the line between the modem and the physical line driver.
It can be used for diagnosing communications problems over a wide
range of protocols, devices, and speeds.
The Datascope is about the size of a small oscilloscope. The
characters on the line are displayed on a small screen. There are
lots of controls for setting the byte size of the characters, the
way in which the bits are to be interpreted, and how the display is
to be formatted.
Some models of the Datascope can be programmed to do things like
search for certain character patterns and stop the display and so
on. Some can be used with a tape unit which can record the line
activity for analysis later.
The Datascope is the best tool we know of for determining exactly
what is happening on a communications line. Unfortunately, it is
very expensive, costing many thousands of dollars. For this reason,
individual offices almost never have a Datascope of their own.
Nonetheless, if you will be doing a network installation or will be
otherwise involved in potentially difficult network problems, it is
a good idea just to inquire into the availability of a Datascope in
case the need for one should arise. Some districts or regions own
one Datascope which can be loaned out to its local offices. If you
are lucky and are involved with a rich customer, the site may have
one of its own. If there is no way you can get your hands onto a
Datascope, a breakout box, which costs only a few dollars, may also
be helpful. This can at least tell you what is happening with the
EIA modem signals and whether data is being sent or received.
The Spectron people offer a course on the use of the Datascope. A
quicker way to learn its use is to simply find someone who knows how
to use it and to ask him or her to show you how it works. The
controls are simple and an hour or two of hands-on time should be
plenty. The remainder of this memo describes how to use the
Datascope.
Page 2
HOOKING UP THE DATASCOPE
1.0 HOOKING UP THE DATASCOPE
The Datascope is hooked into the line between the line driver and
the modem. Plug the EIA connector coming out of the interface for
that line into the back of the Datascope in the position marked "Bus
Mach/RCU". Then patch a plug between the "modem" connector on the
Datascope and the modem. Then power on the Datascope. Note that
the datascope need not be on for the link to work.
2.0 LIGHTS
The row of lights across the display corresponds to the EIA-CCITT
modem-terminal interface. For example, if light 8 is on, it
indicates that Carrier Detect, pin 8, is high. This display is the
same as the display in a breakout box. A listing of the pin numbers
is included later on in this memo.
3.0 DATASCOPE SWITCH SETTINGS
To look at an asynchronous data stream set the switches on the front
panel of the data scope as follows:
Switches:
Name Setting
2 char/normal N/A
Internal/modem Internal
Manual N/A
1-8/8-1 8-1 normal order, bit 1 arrives
first
Send Down - normal polarity
Rcv Down - normal polarity
Both Down - normal polarity
Dials:
Send/Rcv FDX - Display send/receive on
alternate lines (2
lines/timeframe).
Ideal for full-duplex.
Framing ASYNC 8 - Clock 8 bit data bytes
(the bit count includes
the parity bit).
Page 3
DATASCOPE SWITCH SETTINGS
Code A - ASCII is displayed.
Marker FDX - Received data black on white
when CD high (pin 8)
Send data black on white
when RTS high (pin 4)
Suppress OFF - Shows all activity on the
line in both directions.
Time relationships can
be seen.
Thumb-wheels
Speed Set to terminal baud rate per speed
table below.
SPEED TABLE
A - 50 E - 150 I - 1200 M - 3600
B - 74.2 F - 300 J - 1800 N - 4800
C - 110 G - 600 K - 2000 O - 7200
D - 134.5 H - 1050 L - 2400 P - 9600
Framing pattern N/A
Sync reset N/A
Rocker switches
Display Run
Prog Idle
4.0 HEX-ASCII DATA CONVERSION
The following chart can be used to convert 8-bit ASCII to HEX. It
can also be used to obtain the binary for each HEX digit. To
convert from HEX to ASCII, choose the first HEX digit from the top
and the second HEX digit from the left, and then look where the row
and column meet. To convert from ASCII to HEX, choose the second
HEX digit from the row in which the character appears and the first
HEX digit from the column. The reason there are two choices for the
first HEX digit is because parity may be odd, even, or non-existent.
For no parity, choose B8=0. For even or odd parity, choose either
B8=0 or B8=1, whichever one will give you the right number of 1
bits.
Page 4
HEX-ASCII DATA CONVERSION
For example,
ASCII "L" = 4C (no parity)
= CC (even parity)
= 4C (odd parity)
|------------------------------------------------|
| B7----------->|0 |0 |0 |0 |1 |1 |1 |1 |
| B6-------->| 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 |
| B5----->| 0| 1| 0| 1| 0| 1| 0| 1|
|---------------\ | | | | | | | |
| 1st HEX B8=0 \ | | | | | | | |
| Digit ----\ ---|---|---|---|---|---|---|---|
| B8=1 \ 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|--------------\ ---|---|---|---|---|---|---|---|
| 2nd HEX Digit \ 8 | 9 | A | B | C | D | E | F |
|----------- ||---|---|---|---|---|---|---|---|
|B4|B3|B2|B1| || | | | | | | | |
|--|--|--|--|---||===|===|===|===|===|===|===|===|
| 0 0 0 0| 0 ||NU |DL | | 0 | @ | P | ` | p |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 0 0 1| 1 ||SH |D1 | ! | 1 | A | Q | a | q |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 0 1 0| 2 ||SX |D2 | " | 2 | B | R | b | r |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 0 1 1| 3 ||EX |D3 | # | 3 | C | S | c | s |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 1 0 0| 4 ||ET |D4 | $ | 4 | D | T | d | t |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 1 0 1| 5 ||EQ |NK | % | 5 | E | U | e | u |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 1 1 0| 6 ||AK |SY | & | 6 | F | V | f | v |
|-----------|---||---|---|---|---|---|---|---|---|
| 0 1 1 1| 7 ||BL |EB | ' | 7 | G | W | g | w |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 0 0 0| 8 ||BS |CN | ( | 8 | H | X | h | x |
|-----------|---||---|---|---|---|---|---|---|---|
! 1 0 0 1| 9 ||HT |EM | ) | 9 | I | Y | i | y |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 0 1 0| A ||LF |SB | * | : | J | Z | j | z |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 0 1 1| B ||VT |EC | + | ; | K | [ | k | { |
|-----------|---||---|---|---|---|---|---|---|---|
! 1 1 0 0| C ||FF |FS | , | < | L | \ | l | | |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 1 0 1| D ||CR |GS | - | = | M | ] | m | } |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 1 1 0| E ||SO |RS | . | > | N | ^ | n | ~ |
|-----------|---||---|---|---|---|---|---|---|---|
| 1 1 1 1| F ||SI |US | / | ? | O | _ | o |DT |
|------------------------------------------------|
Page 5
EIA PIN DEFINITIONS
5.0 EIA PIN DEFINITIONS
+----------------------------------------------------------------+
| Pin| Name |To To | Function | Circuit |
| | |DTE DCE| |(CCITT) (EIA) |
|----+------+-------+----------------------------+-------+-------|
| 1 | FG | | Frame Ground | 101 | (AA) |
| 2 | TD | > | Transmitted Data | 103 | (BA) |
| 3 | RD | < | Received Data | 104 | (BB) |
| 4 | RTS | > | Request To Send | 105 | (CA) |
| 5 | CTS | < | Clear To Send | 106 | (CB) |
| 6 | DSR | < | Data Set Ready | 107 | (CC) |
| 7 | SG | | Signal Ground | 102 | (AB) |
| 8 | DCD | < | Data Carrier Detect | 109 | (CF) |
| 9 | | < | Positive DC Test Voltage | | |
| 10 | | < | Negative DC Test Voltage | | |
| 11 | | | Unassigned | | |
| 12 | SDCD | < | Sec. Data Carrier Detect | 122 | (SCF) |
| 13 | SCTS | < | Sec. Clear To Send | 121 | (SCB) |
| 14 | STD | > | Sec. Transmitted Data | 118 | (SBA) |
| 15 | TC | < | Transmitter Clock | 114 | (DB) |
| 16 | SRD | < | Sec. Received Data | 119 | (SBB) |
| 17 | RC | < | Receiver Clock | 115 | (DD) |
| 18 | | > | Receiver Dibit Clock | | |
| 19 | SRTS | > | Sec. Request To Send | 120 | (SCA) |
| 20 | DTR | > | Data Terminal Ready | 108.2| (CD) |
| 21 | SQ | < | Signal Quality detect | 110 | (CG) |
| 22 | RI | < | Ring Indicator | 125 | (CE) |
| 23 | | > | Data Rate Select |111/112|(CH/CI)|
| 24 | (TC) | > | External Transmitter Clock | 113 | (DA) |
| 25 | | > | Busy | | |
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