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1.1 root 1: '\" t
2: .TH EM3270 8 DLBA 1.10
3: \" @(#)em3270.8 1.10
4: .SH NAME
5: em3270 \- IBM 327X Terminal Emulation
6: .SH SYNOPSIS
7: .nf
8: .I
9: /usr/bin/em3277
10: .I
11: /usr/lib/bsc/bsclog
12: .I
13: /usr/lib/bsc/bscmon
14: .I
15: /usr/lib/bsc/bsctrace
16: .fi
17:
18: .SH DESCRIPTION
19: .I Em3270
20: is the communal name for the collection of programs and a file
21: organization that allows a computer system to communicate emulating an IBM
22: 3277 interactive terminal.
23: Together with a Bisync communications facility,
24: .I em3277
25: can emulate an IBM 3277 model
26: 2 terminal (Bisync, 1920 character screen).
27: The communications facility
28: itself emulates the functions of the IBM 3271 or 3275 communications
29: control unit to which the 3277 terminal is usually attached.
30: .P
31: The Binary Synchronous protocol, commonly called BISYNC, is a byte-oriented,
32: half-duplex protocol, although full-duplex communications facilities
33: are sometimes used in order to reduce the time required to turn the
34: transmission direction around.
35: A set of control characters are used
36: to provide framing and data transparency; data containing imbedded
37: control characters may be transmitted in a `transparent' mode to
38: avoid conflicts with the protocol control characters.
39: (The IBM 3277 terminal does not use the `transparent' mode.)
40: Communications may be point-to-point, in which case a contention
41: method is used to control the line; communications may also be multi-point,
42: in which case one node is designated the controlling node and polls
43: and/or selects the other nodes in order to control communications.
44: .P
45: In the em3270 system, the administrator designates a collection of
46: one or more hosts to which the computer connects, emulating an
47: IBM 3277 terminal.
48: For each of these hosts, the administrator provides
49: a set of parameters pertaining to that host connection and the specific
50: terminal parameters for emulation.
51: .P
52: A user may utilize almost any asynchronous ASCII terminal to emulate the
53: 3277 terminal, as long as the characteristics of that terminal are
54: listed in the TERMCAP terminal database (see TERMCAP(5)), and
55: the terminal has cursor positioning capability, 24 or more lines,
56: and 80 or more columns.
57: Desirable features are a means of making
58: text "stand out" (highlighting, reverse video, ...) and function
59: keys (including cursor movement).
60: The 3277 special keys are mapped from control or function keys available
61: on the user's terminal; the mapping is specified in the TERMCAP terminal
62: database which is usually maintained by the system administrator.
63: .P
64: A 3277 terminal often has a printer either directly attached or available
65: through the control unit.
66: .I Em3270
67: supports a printer feature; the user may specify that data directed to a printer
68: be stored in a file or directed to another program's standard input.
69: The user may also directly invoke a local print operation.
70: Four print formats are supported: fixed at 40, 64, or 80
71: characters per line,
72: and variable-length, the data having newlines and other
73: format effectors imbedded in it.
74: .P
75: An audit trail can optionally be kept which records all em3270
76: activity.
77: The audit trail logs host, user, and time for various messages
78: about connection and disconnection,
79: various statistics and all errors, temporary or permanent.
80: Once started, the audit trail file grows indefinitely; the administrator
81: is responsible for trimming it back when necessary.
82: .P
83: The em3270 communications interface can be
84: via a leased (dedicated) line, or via dial-up (switched) facilities.
85: If communications are via dial-up (switched)
86: connections, either an operator is required to do the dialing, or
87: there must be an automatic calling unit connected in with the synchronous
88: modem.
89: .P
90: The em3270 utilities do not provide for automatic calling units.
91: However, an installation-written routine can be invoked immediately before
92: host connection and just following host termination
93: to provide for such things as operator instructions or automatic dialing.
94: .P
95: The following diagram shows the relationships between various files
96: and programs used in the 327X emulation process.
97: .TS
98: box,center;
99: c|c|c.
100: DESIRED USER LINK
101: FUNCTION LEVEL LEVEL
102: _
103: Emulate 3275/3277 em3277 /dev/bsc*
104: _ _ _
105: Check status bsclog <dir>/AUDIT
106: _
107: Monitor bscmon, /dev/bsctr*
108: Activity bsctrace
109: .TE
110: .P
111: The designator
112: .I <lib>
113: refers to directory name `/usr/lib/bscbatch/';
114: in this directory are parameter files for each
115: possible host connection (<hostname>).
116: .P
117: The
118: .I <dir>
119: designator refers to the host's spool directory. This name is a combination of
120: the directory prefix `/usr/spool/bscbatch/'
121: followed by the <hostname> directory into which the AUDIT file
122: pertaining to this host will be placed.
123: .P
124: At the beginning of a session (user invokes
125: .I em3277)
126: the utility will read the host parameter file to determine the communications
127: line characteristics \- device to use, terminal identification, ....
128: The communications line will be opened and the terminal's characteristics
129: (determined by obtaining the TERMCAP information for the terminal
130: specified by a TERM entry in the user's environment) noted.
131: A keyboard mapping which allows the 3277 function keys to be emulated will be
132: established, and the user's terminal is now said to be in emulation
133: mode.
134: A special key will be used to terminate the session, invoke
135: system commands, reset the emulated keyboard, cause printing, and establish
136: a file or program to receive all printer data.
137: .P
138: After the user terminates the session,
139: .I em3277
140: terminates the connection to that host.
141: The installation may provide an exit routine to be invoked at this
142: time (immediately after termination of connection) to take care of
143: any necessary cleanup.
144: .P
145: A trace facility can be invoked which records communications events
146: and the time they occur,
147: and optionally records actual data, transmitted and received.
148: The trace information can be placed into a file for immediate or later
149: analysis by another program.
150: The general intent is to provide enough information for communications
151: debugging that a data link analyzer is not necessary.
152: .P
153: The
154: .I bsctrace
155: program interprets trace information provided to
156: .IR bscmon by /dev/bsc*tr.
157: A state diagram provided with the
158: .I bscmon(8)
159: document shows the communication
160: states and flow which makes up the BISYNC protocol; state transition
161: information is provided to
162: .I bscmon,
163: which records
164: it and optionally the transmitted and received data, in a file.
165: .I Bsctrace
166: is used to display this data in a readable format.
167: .SH ADMINISTRATION
168: .SS Installation.
169: The em3270 tape is used in the installation process for the em3270 facility.
170: To install em3270, do the following:
171: .RS
172: .IP 1.
173: Make a directory to contain the installation files, e.g.,
174: /tmp/em3270, then change to that directory.
175: Use
176: .I tar xv0
177: to copy the files from tape to the directory.
178: The following files should be extracted:
179: .TS
180: center;
181: c c c.
182: em3277 em3277.x em.h
183: 3270 3270inst inst3270.c
184: .TE
185: .IP 2.
186: Prepare installation exit subroutines, if necessary.
187: File inst3270.c contains default
188: subroutines for the installation exits, as described below.
189: They may be modified or completely replaced, but must exist.
190: .RS
191: .P
192: .I
193: connect (host, dev)
194: .br
195: .I
196: char *host, *dev;
197: .P
198: is called when
199: .I em3277
200: is ready to make a connection to
201: .I host
202: via device
203: .I devname.
204: The connection will be made only if
205: .I connect
206: returns a zero value; if a non-zero value is returned, a note will be placed
207: in the AUDIT file (if one exists), and
208: .I em3277
209: will terminate.
210: .P
211: This routine may perform auto-dialing or operator communication
212: necessary for connection.
213: The default (supplied) routine merely returns a zero value immediately.
214: .P
215: .I
216: disconnect (host, devname)
217: .br
218: .I
219: char *host, *devname;
220: .P
221: is called when
222: .I em3277
223: has just disconnected from the given host and device.
224: This routine may perform any cleanup necessary
225: at this time.
226: The default (supplied) routine merely returns.
227: .P
228: .I
229: audit (message)
230: .br
231: .I
232: char *message;
233: .P
234: is a routine which may be called by any of the installation-supplied
235: routines which need to place information into the AUDIT file.
236: The single parameter will be written into the AUDIT file along with a
237: time stamp and the current host's name.
238: .RE
239: .IP 3.
240: Install all files. `3270inst' is a shell command file which will link the
241: .I em3277
242: command object files with inst3270.c and
243: install all commands and files into the appropriate directories.
244: .RE
245: .SS "Set Up Host Configurations."
246: For each separate host, a file must be created in /usr/lib/bscbatch
247: which supplies the control and administrative information used by
248: the
249: .I em3270
250: utilities.
251: The file may be created via the text editor.
252: A sample configuration appears in file 3277, extracted in step 1 above.
253: Any of the following parameters may be specified in the configuration
254: file, one parameter per line.
255: The default will be taken for any unspecified parameters.
256: .TP
257: CODE=ASCII\||\|EBCDIC.
258: This specifies the transmission code
259: to be used in the protocol, and what translation is to be performed
260: on transmitted or received data.
261: Default: EBCDIC.
262: .TP
263: CONTROLLER=3271\||\|3275.
264: This specifies the 3277 emulated controller unit, 3271 or 3275.
265: Default: 3275.
266: .TP
267: DEVICE=/dev/bsc*.
268: The device used for BISYNC operations is specified here.
269: Alternate multipoint (polled) device addresses can be specified with
270: lists or ranges (e.g. /dev/bscm0,1,4 or /dev/bscm0-15).
271: Default: /dev/bsc.
272: .TP
273: DUPLEX=HALF\||\|FULL.
274: Specify FULL for a full-duplex modem, HALF for a half-duplex modem.
275: Default: HALF.
276: .TP
277: IDCHECK=hostid.
278: In the BISYNC protocol, allowances are made for erroneous connections
279: in a switched network.
280: The two nodes are allowed to exchange identification
281: in the form of a short sequence of characters added to the initial
282: handshake.
283: If it is desired that the host's identification be checked,
284: and that communications not be allowed to occur unless the identification
285: matches that given here, specify this parameter.
286: The host identification may consist of up to twenty alphanumeric characters.
287: Default: do not check host identification.
288: .TP
289: MAIL=userid.
290: .I Em3277
291: will send mail to the system administrator (name given by
292: .I userid)
293: for any significant problems requiring attention.
294: These include incorrect parameters in this file,
295: inability to connect to host, and host id check failures.
296: Default: messages sent to /dev/console.
297: .TP
298: MPTADDR=aa.
299: .I Aa
300: is the address of the emulated terminal if this is a multipoint network.
301: If this is point-to-point, this parameter must not be specified.
302: .I Aa
303: consists of two alphabetic characters, the first is the polling address,
304: the second the select address.
305: Default: point-to-point mode.
306: .TP
307: NBID=nn.
308: .I Nn
309: is the number of initial handshakes,
310: or `line bids' which will be made when there is no host response.
311: In a multipoint or other leased line arrangement, this value should
312: be zero, which means retry forever.
313: Maximum value for
314: .I nn:
315: 127.
316: Minimum value: 0.
317: Default: 0 (no limit).
318: .TP
319: NNAK=nn.
320: .I Nn
321: specifies the number of NAK's (negative
322: acknowledgement to text block due to CRC error) that the driver should
323: give before terminating communications via sending EOT instead of NAK.
324: This parameter prevents endless transmissions for cases where
325: the text block was actually built incorrectly.
326: Maximum value for
327: .I nn:
328: 127.
329: Minimum value: 0.
330: Default: 16.
331: .TP
332: NRETRY=nn.
333: .I Nn
334: is the number of retries which will
335: be made during transmission where a text block has been NAK'd (received
336: with incorrect CRC, or check characters) or where a text block has
337: had no response from the host (timeout).
338: Maximum value for
339: .I nn:
340: 127.
341: Minimum value: 0.
342: Default: 15.
343: .TP
344: NTTD=nn.
345: .I Nn
346: is the number of TTD's (temporary
347: text delays from host) that the driver should receive and NAK before
348: terminating the receive operation via sending EOT.
349: This parameter may be used to prevent prolonged delays from tying up
350: a communications line.
351: A value of zero will force the driver to always NAK a TTD.
352: Maximum value for
353: .I nn:
354: 127.
355: Minimum value: 0.
356: Default: 150.
357: .TP
358: NWACK=nn.
359: .I Nn
360: is the maximum number of WACK's (wait
361: acknowledgements) the driver will accept while attempting to transmit
362: before terminating transmission via sending EOT.
363: This parameter may
364: be used to prevent prolonged delays while the host computer is unable
365: to accept the next data block due to delays.
366: A value of zero will force the driver to always accept a WACK.
367: Maximum value for
368: .I nn:
369: 127.
370: Minimum value: 0.
371: Default: 150.
372: .TP
373: TERMID=ident.
374: If this parameter is specified,
375: .I ident
376: will be provided to the host as this
377: (emulated 3277) terminal's identification (see
378: .I IDCHECK,
379: above).
380: .I Ident
381: may be a string of up to twenty alphanumeric characters.
382: Default: no identification.
383: .SS "Set Up Host SPOOL Area."
384: For each host, make a directory /usr/spool/bscbatch/<hostname>.
385: If an audit trail is to be kept on this host, create an empty file
386: in that directory called AUDIT.
387: .SS "Regular Maintenance."
388: .P
389: Some minimal maintenance of the host spool areas is required.
390: The administrator's mailbox should be inspected and cleaned out regularly.
391: The audit trail file (/usr/spool/bscbatch/<hostname>/AUDIT) should be truncated
392: via the
393: .I bsclog
394: utility regularly.
395: Most convenient is an entry in crontab \- once per day,
396: .I
397: bsclog -purge=3
398: could be run to discard all but
399: AUDIT information for the last three days (see
400: .I bsclog(8)).
401: .SH "SEE ALSO"
402: .br
403: em3277(1C) \- 3277 terminal emulator
404: .br
405: bsclog(8) \- batch audit trail utility
406: .br
407: bscmon(8) \- bsc monitor/trace utilities
408: .br
409: .I
410: Setting Up UNIX
411: .br
412: .I
413: General Information \- Binary Synchronous Communications,
414: IBM document GA27-3004.
415: .br
416: .I
417: 3270 Component Description,
418: IBM document GA27-2749.
419: .SH "SYSTEM REQUIREMENTS"
420: .SS Modems.
421: If two identical modems (same manufacturer, same options)
422: are used at each end of the communications line, most any synchronous
423: RS-232-C interface modem will function correctly.
424: The following modems
425: are definitely supported:
426: .P
427: .nf
428: Bell 201A3 (2000 bits per second)
429: Bell 201C (2400 bits per second)
430: Bell 208B (4800 bits per second)
431: Bell 209A (9600 bits per second)
432: .fi
433: .SH DIAGNOSTICS
434: .P
435: em3277 <host>: can't open <confdir> configuration directory.
436: .IP
437: The configuration directory for this host couldn't be opened.
438: Check the modes.
439: Processing was aborted.
440: .P
441: em3277 <host>: <devname> cannot be opened for communications.
442: .IP
443: The communications device <devname> for the specified
444: host could not be opened.
445: Either the mode is set wrong, or some other
446: process has the device open.
447: Processing was aborted.
448: .P
449: em3277 <host>: unrecognized keyword, line <l> in <filename>.
450: .IP
451: While reading the host configuration file <filename>,
452: an unrecognized keyword was found on line <l>.
453: Probably a typographical
454: error.
455: Processing was aborted.
456: .P
457: em3277 <host>: invalid parameter for keyword <k> in <filename>.
458: .IP
459: While reading the host configuration file <filename>,
460: keyword <k> was found to have an invalid parameter.
461: Probably a typographical
462: error, but it is also possible that the given parameter was out of
463: range.
464: Processing was aborted.
465: .P
466: em3277 <host>: device <devname> reports modem failure.
467: .IP
468: The named device reported a transmit timeout error.
469: The usual reason
470: for this is that the device did not get a transmit clock signal from
471: the modem.
472: This could be due to improper modem option specification,
473: improper cable to the modem from the computer system, or to not having
474: jumpered the MODEM port for external timing.
475: Transmission is
476: aborted for this host.
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