Hewlett-Packard HP Support Link, HP Support Link II Modems Application Note

 North American Response Centers
HP 3000 APPLICATION NOTE #22
ASYNCHRONOUS MODEMS
Г HEWLETT | February 15, 1987
2 PACKARD Document P/N 5958-5824R2707
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For research and education purposes only.
HP 3000 APPLICATION NOTES are published by the North American Response Centers twice a
month and distributed with the Software Status Bulletin. These notes address topics, where the volume
of calls received at the Centers indicates a need for addition to or consolidation of information available
through HP support services. You may obtain previous notes (single copies only, please) by returning
the attached Reader Comment Sheet listing their numbers.
Note # Published Topic
1 2/21/85 HP 3000 Printer Configuration Guide (superseded by note $4)
2 10/15/85 Terminal Types for HP 3000 HPIB Computers (superseded by note #13)
3 4/01/86 HP 3000 Plotter Configuration Guide
4 4/15/86 HP 3000 Printer Configuration Guide - Revised
5 5/01/86 MPE System Logfile Record Formats
6 5/15/86 HP 3000 Stack Operation
7 6/01/86 COBOL 11/3000 Programs: Tracing Illegal Data
8 6/15/86 KSAM Topics: COBOL's Index 1/0; File Data Integrity
9 7/01/86 Port Failures, Terminal Hangs, TERMDSM
10 7/15/86 Serial Printers - Configuration, Cabling, Muxes
11 8/01/86 System Configuration or System Table Related Errors
12 8/15/86 Pascal/ 3000 - Using Dynamic Variables
13 9/01/86 Terminal Types for HP 3000 HPIB Computers - Revised
14 9/15/86 Laser Printers - A Software and Hardware Overview
15 10/01/86 FORTRAN Language Considerations - A Guide to Common Problems
16 10/15/86 IMAGE: Updating to Turbolmage 8 Improving Data Base Loads
17 11/01/86 Optimizing V PLUS Utilization
18 11/15/86 The Case of the Suspect Track for 792X Disc Drives
19 12/01/86 Stack Overflows: Causes & Cures for COBOL II Programs
20 1/01/87 Output Spooling
21 1/15/87 COBOLII and MPE Intrinsics
NOTICE
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Copyright O 1987 by HEWLETT-PACKARD COMPANY
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ASYNCHRONOUS MODEMS
The Response Centers receive many questions on modems. The first section of this Application Note
provides background on this topic. This includes the theory behind the modem’s operation and interface,
the process of establishing a call, and call disconnection. The next section discusses modem configuration.
The final section is a guide to help you trouble shoot modem problems.
THEORY OF OPERATION
Asynchronous modems are used for data communications over voice grade telephone lines. The term
modem is actually a contraction of the two words MOdulation and DEModulation. The modulation
portion of the modem converts digital pulses to analog waveforms for transmission over a telephone
line and the demodulation portion of the modem converts the analog signal back to digital in a form used
by the terminal or computer. Modulation and demodulation are necessary because it is impossible to
transmit digital l’s and O's through the analog spectrum of the voice grade channel. The voice grade
channel can be represented by the frequency range of 300 - 3300 Hz. used for voice transmission.
Various modulation techniques are employed to convert the digital signals to analog. These include
frequency, amplitude, phase, and quadrature modulation. To transfer data successfully between two
points the modems must use the same modulation technique as well as meet other compatibility
requirements specific to any given modulation scheme. The Hewlett Packard Support Link modems use
frequency shift keyed (FSK) modulation and adhere to Bell 103 compatibility requirements at 300 bits per
second and Bell 212A compatibility requirements at 1200 bits per second. This modem specification is
common within the data communications industry today.
Asynchronous modems are used primarily for asynchronous Data Terminal Equipment (DTE) where the
speed of character generation is random (that is, the delay between characters is random) and detection is
through start and stop bits. HP 3000 DTE which use asynchronous transmission include the ATP and
ADCC as well as all terminals and printers connected to these ports. Another characteristic of
asynchronous transmission is that clocking signals are not used to clock data at precise rates, instead the
modem clocks ON data. Clocking ON data is when the modem transmits the logical condition of a mark
or space (0 or 1) over the communication channel (phone line) as long as it is present on the interface from
the DTE. Hewlett-Packard does not support synchronous modems used on asynchronous ports.
Hewlett Packard packages and sells two asynchronous modems for use with the HP 3000. These are the
older "HP Support Link" manufactured by Racal Vadic and the "HP Support Link IT" manufactured by
Andersen Jacobsen. The Support Link II is the modem presently being shipped with each HP 3000 for
remote telesupport, HPTrend, and Predictive Maintenance. Both of these modems are Bell 212A and Bell
103 compatible providing full-duplex 300 bps asynchronous operation in the low speed (103) mode and
full-duplex 1200 bps asynchronous operation in the high speed (212) mode. Other modems can be used in
conjunction with the HP Support Link modems only if they are Bell 103 or 212A compatible modems
which operate in full duplex mode. Full duplex refers to the fact that data can travel from local to
remote or vice-versa simultaneously as opposed to half -duplex where data can only travel in cne direction
at a time.
MODEM INTERFACE
In order for the DTE to communicate properly with the DCE, (Data Communications Equipment or
modem), the two must follow some kind of interface rules. Hewlett Packard asynchronous transmission
adheres to the RS-232C interface standard as presented by the Electronics Interface Association. RS-232
defines the electrical, mechanical and functional aspects of the interface between DTE and DCE. Part of
this recommendation is the definition of the 25 RS-232 signals. These signals each have a defined use.
However, not all of these pins are required to establish and conduct DTE to DCE communication and vice
versa. The modem (data set) end of the 30062B cable matches the RS-232 standard pin-outs as listed
below:
SIGNAL GROUND Pin 7 1s the ground reference for interface signals.
TRANSMITTED DATA Pin 2 on the DTE is used to send data. This signal is held high or at mark
when the line is idle.
RECEIVED DATA Pin 3 on the DTE is used to receive data. This signal is held to a mark
when the modem 1s idle or carrier detect is off.
CARRIER DETECT Pin 8 is raised by the DCE to show that data carrier is being received from
the distant modem.
DATA SET READY Pin 6 is raised by the DCE to show the DTE that the modem is on and
connected to the telephone line.
DATA TERMINAL READY Pin 20 on the DTE is provided by the DTE to allow the modem to enter
and remain in the data mode. When on, it allows the modem to
automatically answer an incoming call. When it goes off it commands the
modem to disconnect the line at the end of the call.
REQUEST TO SEND Pin 4 on the DTE is used to tell the modem to prepare for transmission and
is used to indicate that the DTE wants to transmit data. RTS is always held
high in full duplex operation.
CLEAR TO SEND Pin Son the DCE is raised to tell the DTE it can transmit. CTS 1s always
held high in full duplex operation and is not monitored by the HP 3000
with subtype 1 but 1s monitored with subtype 9.
Note: Refer to the Data Communication Handbook (Part No. 5957-4634) for a complete diagram on the
pin-out for the 30062B cable.
Establishing a Call
The process of establishing a call consists of dialing the telephone number of the remote modem, raising
the appropriate RS-232 signals and transferring control from the DCE to DTE where communication
must ultimately start or end. The RS-232 signals required by an HP 3000 asynchronous port and remote
device before communication can begin are DSR (data set ready) and CD (carrier detect). In addition, the
modem requires DTR (data terminal ready), and RTS (request to send). Many modems can be strapped to
keep the CD and DSR signal high. This may be helpful in applications such as auto calling. In order to
raise the RS-232 signals in the correct order special timers are used by the modem. If the signals are not
raised in this order the remote or local modem may interpret a situation incorrectly and drop the
connection. In addition, modems must send special frequencies to disable echo suppressors, initiate telco
billing and communicate call establishment state. For further discussion on call establishment see the "HP
Data Communications Testing" manual which documents call establishment and disconnection.
Call Disconnection
Call disconnection begins when the initiating DTE drops DTR for at least 50 ms. The responding modem
will then drop DSR and CD after a timer has expired. Soon after DSR and CD on the initiating modem
will also drop. This ensures proper disconnection of the responding modem and closes the the HP 3000
port. If DSR and CD are held high as in the case of auto dialing, the HP 3000 will have no way of
knowing a session should be aborted if the modem disconnects before the user types BYE. As a result the
next call to the modem will log right into the last users active session. Therefore, HPtrend users and
Predictive Maintenance users who have auto dial configurations on their modems should consider
configuring this modem for originate only or should disable auto answer capability.
MODEM CONFIGURATION
Modem configuration differs for various modem applications. For simple remote telesupport or user
applications the factory default settings for the modem are most likely sufficient. For HPtrend and
Predictive Maintenance use however, the modem must be configured carefully. The "HPTREND Users
Guide" documents correct modem configuration for HPTREND use. Predictive Maintenance
configuration is done by an HP representative, usually the account CE. Keep in mind that these
configurations may be using auto dial and therefore pose a possible security threat.
The HP 3000 port configuration will look like any asynchronous device using the port except for the
subtype parameter. The subtype determines speed sensing characteristics as well as what modem and
timing signals will be needed. The configuration for an asynchronous terminal and an explanation of all
the possible subtypes are given below:
LOG DRT U C T SUB TERMINAL SPEED REC OUTPUT MODE DRIVER DEVICE
DEV # N H Y TYPE TYPE WIDTH DEV NAME CLASSES
# I A P
TN E
ttt u w 0 16 zz 10 120 40 WWW JAID XXXXXIXX YYUYYYYYY
ttt logical device number of the modem port
u appropriate DRT for the modem port
LY appropriate unit number for the modem port
WWW output device number (same as the logical device)
LLXLLLXLX driver name for your type of terminal hardware and operating system
yyy yy yyy any device class name such as MODEM
zz modem subtypes
Modem Subtypes:
1 Used with asynchronous full duplex modems. Compatible with Bell 103, 202T, 212A and CCITT
V.21 modems requiring speed sensing. ATP and ADCC (HIOTERM2) require DSR (data set
ready), and CD (data carrier detect).
5 Identical to subtype 1 except that automatic speed sensing is disabled. This subtype is not
supported on ATP ports running ATP software prior to G. 50.83. It is supported on the ADCC
prior to MPE V/E and after ADCC version G. 50. 85.
9 Supported on ATP and ADCC (HIOTERM2) ports. Asynchronous CCITT modem that requires
monitoring CTS (Clear to Send), otherwise identical to subtype 1. Monitoring Clear To Send
will allow the DTE to transmit data only when CTS is high. This is required in several European
countries.
10 Supported on the ATP only (С. 50. 83, UB-Mit version, and above). This subtype is the same as
subtype 1 except no speed sense timer is started when DSR and CD are raised.
11 Identical to subtype 10, except that automatic speed sensing is disabled.
15 Modem subtype for asynchronous printers, otherwise identical to subtype 1.
ASYNCHRONOUS MODEM TROUBLE SHOOTING
Trouble shooting an asynchronous modem port can be done in a systematic and timely manner. If a
connection to the HP 3000 can not be made you must identify all the devices and software needed to
create the connection and you must test each one alone and in conjunction with the others. If your
problem is with Hptrend or Predictive Maintenance, keep in mind that your problem may be related to
the software needed to use these products. The Response Center will be happy to help you through any
portion of the trouble shooting process.
The first step in trouble shooting is verification. That is, making sure everything is configured and set up
correctly. A surprising amount of modem related problems are solved by simply verifying configuration
and checking to make sure devices are powered on, ready for use and correctly attached to the proper
port. It is a good idea to perform a quick inspection of all connections. Verify that the proper cable is
being used and that it is connected properly. Configuration can be verified by consulting the appropriate
manual. The HP 3000 System Operation and Resource Management Reference Manual can be used to
verify 1/O configuration. To verify modem configuration you should have a manual for your modem
With the required configuration parameters penciled in or have the needed parameters written down.
This is a good idea because modem manuals can be confusing to a non-data communication expert and
modem configurations often change depending on what application you are using, (ie. HPtrend). If you
don’t have a manual for your modem it would be a good idea to get one. The part number for the HP
Support Link users guide is 35141-90001 and the part number for the HP Support Link II Users Guide is
35031-90001.
If you are reasonably sure that everything is correct, the next step is to get an idea of where the problem
is occurring. Is the modem dialing out? Is the remote modem answering? Can you get a colon prompt?
Many times the modems themselves are working fine but you can not establish communication between
the modem and the computer port. Other times the modems may work fine but the terminal itself is not
communicating properly with the remote modem. To find out where you are in the call process take a
look at the remote modem first. Is the modem dialing out? If not, your problem is with the remote
terminal or modem. If the modem seems to be dialing out properly according to lights on the modem or
on a breakout box, check to see if the modem on the computer port is answering. If not, you may have a
bad phone line or local modem configuration. Finally, if the local modem answers the call but no
connection can be established, you could be dialing into an incompatible modem or improperly configured
port. Look into factors such as port speed and configured parity. Also, you should concentrate on the HP
3000 and the local modem connection. The next section is a guide to follow when trouble shooting
modem problems.
SYMPTOM:
¢ Your remote modem 1s not dialing out.
PROBLEM SOLVING STEPS:
1. Verify the modem configuration.
2. If you dial out from the terminal, verify that your terminal is in remote mode and set at the
correct baud rate. Also verify that you have the correct cable.
3. Make sure you can get a dial tone on the phone line. If your modem is auto dial, plug in the
appropriate phone type to the (pulse or tone) RJ-11 jack, and see 1f you can call someone.
4. Test the modem with self test and local analog loopback tests as documented in your modem
manual.
SYMPTOM;
¢ Your remote modem is dialing out but the local modem is not answering, or it answers then
immediately drops the connection.
PROBLEM SOLVING STEPS:
1. Make sure you have the correct phone number.
2. Verify modem configurations.
3. Make sure you can get a dial tone on the local phone line. Plug in the appropriate phone type
to the RJ-11 jack and see if you can call someone.
4. Try dialing out to another computer port.
5. Try performing remote digital loopback from the remote side. If this is possible it will be
documented in your modem manual.
6. Check the lights on the modem, DTR must be on.
7.
SYMPTOM:
Run TERMDSM to determine if the port is "broken". (Refer to Application Note #9 Port
Failures, Terminal Hangs, TERMDSM for a complete description on using TERMDSM.)
Your local modem answers but you can’t get a colon prompt.
PROBLEM SOLVING STEPS:
1.
Verify the HP3000 I/O configuration is correct and that you have the correct cable (and that
it is not connected backwards). The HP recommended cable type is number 30062B (Part
No. 30062-60022 or 30062-60023).
Do a :SHOWDEYV on the port. To be able to log on, the results must be: 21 A AVAIL or 21
J AVAIL. The "A" indicates the port is JOB and DATA accepting, the "J" indicates JOB
accepting only. If the port is "AVAIL" but neither "J" or "A" appears, issue an :ACCEPT ldev.
If the port is down, issue the :UP Idev command from the console. If the port is "21
UNAVAIL SYS" the port has received a modem signal interrupt (ie., DSR and/or CD
becoming high) or the <CR> has been sensed. The port should be in the process of logging on.
If the port shows "21 UNAVAIL % 528,2 FILES" a session already owns that port.
. Verify modem configuration by checking the actual configuration against a configuration
listing.
. Tf possible, try another cable or HP 3000 port.
. Verify the remote terminal has the correct baud rate and parity. For a terminal on a subtype
10 port the baud rate should be set to match the baud rate configured on the port and the
parity should be Os. If the port is set to 120 cps. then the terminal should be set to 1200
baud.
. Make sure the local modem is working properly. The modem should have a self test that is
documented in the manual. In addition you can disconnect the modem from the port and
attach it to a terminal with a straight through cable, and perform an analog loopback test as
documented in the modem manual. This tests the modems ability to convert digital to analog
and vice versa. `
Run TERMDSM to see if the port is broken.
READER COMMENT SHEET
North American Response Centers
HP 3000 Application Note #22: Asynchronous Modems
RC Questions & Answers (February 15, 1987)
We welcome your evaluation of this Application Note and attached RC Questions & Answers Sheet. Your
comments and suggestions help us to improve our publications. Please explain your answers under
Comments, below, and use additional pages if necessary.
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Document P/N 5958-5824R2707 February 15, 1987
WLETT
M Packann RESPONSE CENTER QuesTions & ANSWERS
HP 3000 Quest ions Commonly Received by the North American Response Centers
| Q. I just updated to MPE version G. 02,01 (UB-Delta-1) and now I am getting SPOOLEE 1/0 ERROR
; %53. Do you know what the problem is?
6 A. Yes. There isa problem with the ATP/ADCC software that was shipped with UB-Delta-1 which will
cause intermittent port failures accompanied by console messages such as ATP FAILURE 6706 and
SPOOLEE I/O ERROR %53. A patch which corrects the problem will be shipped to those who received
the defective software. If you receive the patch you should install it on your system.
Included with the patch will be a letter covering the installation instructions. Following are further
comments to assist you with the installation:
l. Restore all files to PUB.SYS (there are 11 files)
Before beginning the installation ensure that you have a backup of @ PUB.SYS.
Use the RESTORE command to restore all files on the tape into the PUB group of the
SYS account. Note that there are 11 files. Save the file list.
2. :STREAM JOSJ196A
0 | | Use the EDITOR to insert the appropriate passwords in the jobstream
JOSIJI96A.PUB.SYS. The job will log on as MANAGER.SYS. Make sure
MANAGER. SYS 1s homed to the PUB group.
STREAM the JOSJ196A.PUB.SYS job. This job will PURGE the TERMDSM
program, so if the job aborts, make sure that the TERMDSM program is RESTORED
from a backup tape.
3. This jobstream will create an update tape.
4. Update your system with this tape.
Update your system with a COLDSTART.
5. Verify that the patch has been successfully installed by:
a) running TERMDSM.PUB.SYS
b) The ATP version listed will be G.87.89
c) The ADCC version listed will be G.87.19
en: a
x me
If you do not want the patch files to be in PUB. SYS, you may remove them.
The patch has been incorporated in the release of future UB-Delta-1 (Version G.A2.01) shipments. If
the label on the UB-Delta-1 tape has a VUF of G. A2.01 then you will not need to install the patch. You
can verify that you have the correct software by following step $ above.
more...
A.
After updating to MPE version G. 02, во 0 (UB-MIT) I can no longer use NS/LAN. I get the message
MISSING DADCONF. NET. sys CONFIGURATION FILE (DSERR 661)
when I issue NSCONTROL START. ae
For UB- MIT and later installations of the NS/ 3000 and OfficeShare e LAN/ 3000 producte (HP 32344
and HP 30240), you need an additional: configuration file. After completing the normal sequence of
NS/LAN 3000 product configuration: steps you should :STREAM. CONFJOB.NET.SYS to create
DADCONF,. NET. SYS.
I just had a power failure and now everything is printing four inches to the right on my printer, the
left margin is in four inches, How do I fix this?
To reset the margin on your printer, issue the following command at your console:
: DOWN LOAD Idev ¿MARGIN=1
where Ildev is the logical device number of your printer.
I used FCOPY to copy COMMAND. mun my terminal screen. I noticed that it contained several
entries for accounts which had been deleted. How can I clean up COMMAND. PUB, SYS?
When your users are off the system, do the following:
1. Log on as Manager. Sys, Pub.
: HELLO MANAGER. SYS, PUB
2. Purge the COMMAND. PUB. SYS file.
: PURGE COMMAND. PUB.SYS я
3. Use the BULDACCT job, which is located in the TELESUP account, to create a job stream
called JOBCUDC.
:RUN BULDACCT.PUB. TELESUP |
Note: BULTACCT will also create two other job streams: JOBACCT and JOBACCTB. Be
sure to purge these jobs since they contain password information and they are not needed.
4. Rebuild the COMMAND. PUB. SYS file.
: BUILD COMMAND. PUB.SYS;REC=128,1,F , BINARY; DISC=1023,8,2
5. Stream JOBCUDC to add entries into COMMAND. PUB. SYS.
:STREAM JOBCUDC |
6. Use FCOPY to view the contents of COMMAND.PUB.SYS. You will see that the file has,
indeed, been cleaned up. -
:FCOPY FROM=COMMAND. PUB. SYS; TO=
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