BARR/3270 manual

10. Communications Diagnostics

With BARR/3270’s extensive communications diagnostics, you can monitor activity between the PC and mainframe, perform loopback tests on the adapter, cable, and modem, save a copy of memory to disk, record line trace on disk, display bind data, and send commands to VTAM.

• 10.1 Communication Scope: SDLC

• 10.2 Communication Scope: Token Ring

• 10.3 Logon Error Messages

• 10.4 Diagnostics

10.1 Communication Scope: SDLC

The BARR Communication Scope shows the activity between your PC and the central host computer. With a look inside BARR/3270, you will not be dealing with a black box.

The BARR Communication Scope appears on the top line of the screen at Logon. When a message is sent, green characters appear; when a message is received, magenta characters appear. For a monochrome display, the message sent is standard, and the message received is in reverse video.

In this manual, the characters received are in reverse video and the characters sent are not.

Dial-up Scope Characters for PC-SYNC Modem

The dial-up characters are the first characters you will see on the Communication Scope if you have a PC-SYNC internal modem. The dial-up characters appear white on a color screen.

A – Answer tone. Host modem sent answer tone to remote.

B – Busy. Host modem is busy.

D – Dialing. Dialing from a PC-SYNC Modem.

N – No answer. No answer tone detected. PC-SYNC modem will redial.

R – Ringing. Host modem is ringing.

Examples of Dial-up Communication Scope

DB – Dialing/Busy. Messages from PC-SYNC modem.

DRA – Dialing/Ringing/Answer. Messages from PC-SYNC modem.

DRND – Dialing/Ringing/No answer tone/Redialing. Messages from PC-SYNC modem.

Mode of Physical Unit

An SDLC physical unit is in one of two modes:

• Normal Disconnect Mode – Unit is not functioning. BARR/3270 is in Normal Disconnect Mode when it starts.

• Normal Response Mode – Unit is functioning.

SDLC Scope Characters

0-7 – Information frame. Frame number of information frame.

Disc – Disconnect. Host sends Disc to force remote into Normal Disconnect Mode.

Dm – Disconnected mode. When the remote is in Normal Disconnect Mode and the host sends frames which the remote cannot process, the remote sends Dm to request an Snrm. This should only occur when the program is restarted.

Frmr – Frame reject. A frame was not correctly formatted. This should never occur.

Rej – Reject. The sender of the Rej has received an information frame incorrectly and is asking for it to be sent again. This is only used for full-duplex communications.

Rnr – Receive not ready. Sender is unable to receive any information frames. Try increasing Memory Allocated For Buffers to 400,000. This is under Tuning Data in Addtional Parameters. See Section 6.4.

Rr – Receive ready. Sender is ready to receive information frames. During idle periods, you will see Rr messages bounced back and forth.

Snrm – Set normal response mode. Host sends Snrm to remote which sets Normal Response Mode.

Snre – Set normal response mode extended. Host sends Snre instead of Snrm when modulo 128 sequence numbering is to be used.

Ua – Unnumbered acknowledgment. Positive response to an SDLC command such as Snrm.

Undf – Undefined. Unrecognized frame received. This should never occur.

Xid – Exchange identification. Host sends Xid to request identification of the remote.

Xidr – Exchange identification response. Remote sends identification data IDBLK and IDNUM. This data defines a Switched Physical Unit in a VTAM library.

! – Illegal. When this follows a received frame (for example, Rr!), the frame was not correctly formatted or is illegal in this mode. This should only occur when the program is restarted.

Communication Scope Characters Indicating Errors

A – Abort. Frame ended with 1111111 (seven consecutive 1s), not with a frame character.

C – CTS failure. Clear-To-Send signal is not available from modem.

E – Error with Cyclical Redundancy Check (CRC) of frame. CRC check characters received did not match the CRC characters computed. For example, noise on the telephone line could cause a bit to be lost in the frame. This would be found when the CRC computed on the bits in the frame received does not agree with the CRC value of the frame sent. The SDLC protocol causes this frame to be re-sent.

N – Non-productive receive. None of the frames received in the last 5 seconds match the SDLC address, or they were random noise frames.

Q – Queue overflow. More frames received than buffers available. Try increasing Memory Allocated For Buffers to 400,000. This is explained in section 6.3, Tuning Data in Additional Parameters.

T – Time out. No answer for 3 seconds.

V – Overrun of receive buffer. The ending frame character was not found before the buffer was filled.

X – Equipment error. Send overrun or receive overrun. Usually caused by LAN or hard disk turning off interrupts. Use DMA for Synchronous Communications? Yes from Interrupt Request, Address, and Loopback Test screen. See Section 5.

If the X Communication Scope message indicating Equipment Check is related to typing on the keyboard, you can use the TSR program BIOS_KEY from the BARR distribution disk. This program only turns interrupts off for brief periods of time.

Examples of Communication Scope

DRAXidXidrSnrmUaRrRr00

Normal Dial-up Sequence.

DRAEETTTTTT

Modem answered but NRZI probably needs changing. See Section 5.3.

DRAXidXidrTTTTT

The Xid failed. Probably IDBLK and IDNUM are not correct. See Section 5.3.

RrRrRrRrRrRr

Line is idle. No information frames are being exchanged.

0123456RrRr7012345RrRr

Host is sending information. Remote is idle.

01234Rr4567012Rr5670123Rr

Both host and remote are sending information.

012E456RrRr3456701RrRr

Frame 3 received in error. Communication resumed at frame 3.

Examples of Dedicated Line Communication Scope

SnrmUaSnrmUa

We can hear the host but the host cannot hear us. Try setting the Constant RTS=Yes. See Section 6.5.

TTTTT

Try changing NRZI. Then ask about modem connection. See Section 5.3.0.

10.2 Communication Scope: Token Ring

The BARR Communication Scope shows the activity between your PC and the central host computer. With a look inside BARR/3270, you will not be dealing with a black box.

The BARR Communication Scope appears on the top line of the screen at Logon. When a message is sent, green characters appear; when a message is received, magenta characters appear. For a monochrome display, the message sent is standard, and the message received is in reverse video. In this manual, the characters received are in reverse video and the characters sent are not.

Scope Characters

0-7 – Information frame. Frame number of information frame.

A – Open. Open the Token Ring adapter. Only performed if not already opened.

Adap – Adapter error. An adapter error has occurred during a connection. Number that follows indicates reason, described in Token Ring Network Adapter Reference, page 7-45.

C – Connection established.

Enn – Error status returned from PC Token Ring Adapter. The codes nn are defined in Token Ring Network Adapter Technical Reference, page 7-2.

EO9 – Adapter not initialized.

E0C – Adapter not opened.

E22 – No response from host.

E43 – SAP already in use.

E46 – Resources unavailable.

I – Initialize. Initialize the Token Ring adapter. Only performed if not already initialized.

L – Open link station. Allocating a link station prior to making a connection when in host mode.

Pc – Computer error. A hardware error is indicated.

Ring – Ring error. The adapter has detected a Token Ring error.

S – Open SAP. Allocating and opening a Service Access Point.

Sabme – Set Asynchronous Balanced Mode Extended Request Received. A request for connection has been received from the host.

Stat – Status request. E09 and E0C are valid normal responses. Other status may indicate adapter errors.

T – Time out. No response from the host adapter.

Undf – Undefined. Unrecognized frame received. This should never occur.

Xid – Exchange identification. Remote sends Xid to tell host that it wants to make a connection. Host sends Xid to request identification of the remote.

Xidr – Exchange identification response. Remote sends identification data IDBLK and IDNUM. This data defines a Switched Physical Unit in a VTAM library.

Xidz – Exchange identification. Remote sends Xidz to host Token Ring Address to request routing information.

Xidrz – Exchange identification response. Host Token Ring adapter or TIC returns routing information.

Examples of Communication Scope

StatIASXidzXidrzXidXidXidrC00

Normal connection if adapter has not been opened. IA indicates initialization and open.

StatSXidzXidrzXidXidXidrC00

Normal connection if adapter has been opened by other software (for example, network software).

StatSXidzE22

Indicates that the host Token Ring Address entered in the Communication Link cannot be located on the Ring.

StatSE43

Requested Service Access Point, SAP, is already in use. Other communication software may be using BARR default Service Access Point.

StatSE46

Resources are available to open a service access point. When adapter was first opened by LAN software too little memory was reserved.

10.3 Logon Error Messages

The following example describes a common error condition at Logon.

Example:

Output on Console:

Reason: PU definition in VTAM specifies more LUs than the NCP MAXLU parameter.

10.4 Diagnostics

Diagnostic programs built into BARR/3270 make it convenient to troubleshoot communications and hardware problems.

From the Diagnostics screen:

Select Communications Statistics.

Communications Statistics

The Communications Statistics command displays the statistics of the communications activity from the beginning of the BARR/3270 program. The statistics are helpful for showing the reliability and use of the communications line.

Example:

Press any key (except r), or press r to reset counts to 0.

Messages requiring explanation are described below. These messages are only relevant for SDLC.

buffers free

Number of free communication buffers in program.

checkpoint retransmissions

Number of times we started retransmission of SDLC information frames because a poll frame sent from the host did not acknowledge all previously sent frames. Probably a frame was received by the host with a CRC error.

equipment errors

Transmit underruns or receive overruns (X on Communication Scope); usually caused by LAN or hard disk turning off interrupts.

extra polls received

Number of times we received a second SDLC poll before we could send the previous poll back. This should always be zero.

frames received out of sequence

Number of SDLC information frames received with the wrong sequence number; a previous information frame probably had a CRC error. The out-of-sequence frames are discarded, and the host is asked to retransmit the lost frame.

full duplex frames received

Number of SDLC frames received while we have the poll and are able to transmit. For half-duplex operation, this will always be zero. If this remains zero after Logon during full-duplex operation, your remote is defined to the host as half duplex; the remote definition must be changed.

Rej frames received

Number of Rej frames received. Rej is sent in full-duplex SDLC when an information frame is rejected because it was received out of sequence.

Rej frames sent

Number of Rej frames sent. Rej is sent in full-duplex SDLC when an information frame is received out of sequence.

Rej retransmissions

Number of times we started retransmission of SDLC information frames after a Rej frame was received from the host. Probably a frame was received by the host with a CRC error. Rej is only used in full-duplex SDLC.

undefined frames received

Either undefined SDLC frames, or frames illegal in the current SDLC mode.

Line Trace

A trace of all information frames transferred between the host and remote can be written to the file named DUMP.

The file DUMP can be viewed in DOS background by the LIST program described in the Systems Integration Notes.

From the Diagnostics screen:

Select Line Trace.

Line Trace options:

Make choices.

Bind Data

Bind data defines the operation rules for each party on the session. This option displays the bind data. The bind data originates from the VTAM LOGMODE table, physical unit definition, and the RJE System.

From the Diagnostics screen:

Select Bind Data.

The screen displays all the bind data for all the LUs.

Use the up and down arrows to scroll through the LUs. The blank LU number shows typical bind data.

The bind data corresponds to the LOGMODE data (Mode Table Entry) described in Section 5.3.

VTAM Commands

The most common use of the VTAM commands is sending the IBM test command to verify that VTAM is operating. It will return a message with the 48 most common characters. Commands can be sent from any of the active logical units.

From the Diagnostics screen:

Select VTAM Commands.

Type logical unit number and command.

Memory Dump

Technical support personnel at Barr Systems, Inc. can diagnose unusual communications problems by examining a copy of memory.

From the Diagnostics screen:

Select Memory Dump.

BARR/3270 writes a copy of memory to disk in a file named DUMP. Then copy this file to a diskette and send it to Barr Systems, Inc.