Siemens SIMATIC TIWAY 1 B.5 ERRORS AND ERROR RECOVERY

USING THE BDLC PROTOCOL

UNILINK HOST

ADAPTER B–10

USER MANUAL

B.5 ERRORS AND ERROR RECOVERY

BDLCs design includes methods for detecting and correcting transmission

errors so that message integrity is assured. Methods are provided for busy

condition, N(S) and N(R) sequence errors, BCS errors, invalid commands, and

timeouts.

B.5.1 Busy

Condition

When either the host computer or the adapter temporarily cannot receive or

continue

to receive I-Frames or UIs because

of internal buffer limitations, that

station

alerts the sending station

by transmitting an RNR with N(R) set to the

count that it expects to receive on the next frame. The busy station should

continue

to respond with RNR until

buffer space is available, while the sending

station

should respond with RR.

A “busy condition” on an adapter will be forced clear whenever the host

computer

sends a SNRM.

B.5.2

N(S) Sequence Err

or

An N(S) sequence error occurs when a receiving station receives a BCS error

free I-Frame that contains an N(S) sequence number not equal to the internal

receive count. The receiving station does not increment its receive count and

responds

with a REJ with the N(R) set to the message it expected to receive. If

the receiving station is the host computer, it can optionally issue a SNRM to

reset

the adapter

’

s sequence counts.

B.5.3

N(R) Sequence Err

ors

An N(R) sequence error occurs when a receiving station receives a BCS error

free

I-Frame that contains an N(R) sequence number not equal to the internal

send

count. If the receiving station is the host computer

, it should respond with

an RR to acknowledge the last frame received correctly or should send a

SNRM

to

reset the adapter

’

s sequence counts.

If the receiving station is the adapter, it will respond with a FRMR indicating

the

condition causing the error

. FRMR is further described in Paragraph B.5.7.

Contents

Main CHAPTER 1 UNILINK HOST ADAPTER Figure 11 UNILINK Host Adapter 1.1 INTRODUCTION 1.2 FEATURES Figure 12 Personality Interface Module (PIM) UNILINK HOST ADAPTER13 USER MANUAL Figure 13 UNILINK Host Adapter Block Diagram Figure 14 UNILINK Host Adapter Physical Features Page 1.3 TYPICAL NETWORK APPLICATIONS Figure 15 Single Host Network Figure 16 Multiple Host Network 1.4 TIWA Y I SYSTEM CHARACTERISTICS Figure 17 TIWAY I Network 1.5 INSTALLATION ASSIST SER 1.7 CUSTOMER 1.6 TECHNICAL OPERA TION AND APPLICA Figure 21 Command String Structure TION 2.1 INTRODUCTION Figure 22 Performance vs Commands Figure 23 Host Computer To UNILINK Host Adapter Communications 2.3 FUNCTIONAL ORGANIZATION AND OPERATING MODES HIU NM HIU NM MHIU Figure 26 Master Host Interface Unit Diagram Figure 27 Typical Single Host Network Figure 28 Typical Multiple Host Network Figure 29 NM Network Figure 210 Standalone NM Network 2.4 TIWAY I HOST SOFTWARE SUPPORT Page 2.5 SETTING THE OPERATING MODE Figure 211 Dipswitch Positions Page Page Figure 212 Standalone Network Manager Dipswitch Settings Page 2.6 SPECIAL NETWORK MANAGER FEATURES Page Page 2.7 THE HIU AS A SECONDARY Page 2.8 MODE INDEPENDENT OPERATIONS Figure 213 External Input/Output Points Example Application Page Page Page Page Example 21 BROADCAST/POLL Example Page 2.10 EXTENDED NETWORK OPERATIONS Table 21 Configuration Modes Supporting Macros Page Figure 214 The Parts of a Macro Example 22 Macro Memory Requirements Figure 215 Host Computer Multiprocessing Application Example Page No (END) Yes Figure 216 Macro Setup Procedure Figure 217 Relationship Between Source Ids and Macro Buffers Page Figure 218 Macro Command Frame T able 22 Macro Types Page Example 23 Macro Options Byte Bit Coding Table 23 MRSW Values Page Page Figure 219 Link Macro Store and Forward Operation Page Page Page Page CONFIGURING THE HOST COMPUTER POR Figure 31 Host Computer Interface T 3.1 THE HOST COMPUTER INTERFACE 3.2 RS232C/RS423A PHYSICAL INTERFACE Figure 32 Host Communications Port T able 31 RS232C/RS423A D Connector Pin Assignment Figure 33 Dipswitch Locations Figure 34 Cable For Connecting To DTE Equipment (Null Modem) Figure 35 IBM PC/AT 9-Pin Null Modem Cable Diagram Figure 36 Multidrop Host Interface Circuit You should select half-duplex operation for the modems when you multidrop to prevent the network modems from simultaneously raising the carrier. Page 3.3 HOST PORT COMMUNICATIONS : Figure 37 NITP Message Structure Page Page Page Figure 310 NITP Dipswitch Settings Both the BDLC and NITP protocols are asynchronous data link layer protocols. Table 32 Host Port Baud Rates Figure 311 BDLC Protocol Dipswitch Settings T able 33 BDLC Protocol Address 3.4 HOST COMMAND TIMEOUT TIW Y I NETWORK POR A TS 4.1 NETWORK PORTS Figure 41 Local Line Interface Ports Table 42 Local Line Connector Pin Assignments PM550 CIM users should refer to Appendix C for different media length factors. Figure 42 TIWAY I Bus Structure Figure 43 Number of Local Line Secondaries vs. Cable Distance Figure 44 RS232C/RS423A Modem Interface Ports Table 43 RS232C/RS423A D Connector Pin Assignment Page Page 4.3 TIWAY I HDLC NETWORK PROTOCOL Figure 46 HDLC Frame 4.4 SETTING THE NETWORK PORTS PARAMETERS Figure 47 Network Port Dipswitch Settings HOST COMMAND SET REFERENCE 5.1 INTRODUCTION Figure 51 Command String Structure Page Page Page Table 51 Secondary Addresses Figure 53 Active Command Tree 5.2 ERROR RESPONSE 5.3 BASE HIU COMMANDS Page Page Page Page Page Page Page Page Page Page Page 5.4 THE EXTENDED HIU COMMANDS Page Page Figure 54 CONFIGURE HIU Command Option 01 Bit Map Table 52 Baud Rates Page Figure 55 Dipswitch Values Bit Map Figure 56 Source Id/Macro Buffer Relationship In addition to the bytes specified, 22 bytes will be added for header information. If number this total count is an odd Page Page Figure 57 Macro Options Byte Page Page Table 53 MRSW Values Page Page Example 5-1 ENABLE/DISABLE MACRO EXECUTION Command Example 5-2 ENABLE/DISABLE MACRO EXECUTION Response Page Page Page Page Page Page Page Page Page Page 5.5 ADAPTER CONFIGURATION COMMANDS If the first command sent to the adapter is one of the Base HIU commands, the adapter will automatically begin operation in the Emulate Host Adapter (EHA) mode and the defaults for this command will be assumed. Page Figure 58 Dipswitch Values Bit Map 5.6 NETWORK MANAGER COMMANDS Page Table 54 Option Code 01 Bit Map Table 55 Baud Rates Page Figure 59 Option 09 Bit Map Page Figure 510 Dipswitch Values Bit Map Page Figure 511 Link Status Byte Bit Map Page Page Page Page Page Page Page 5.7 MODE INDEPENDENT COMMANDS Page Page Page Page 5.8 COMMAND SYNT AX QUICK REFERENCE Page Page Page 5.9 COMMAND CODES REFERENCE (NUMERICAL ORDER) 5.10 COMMAND CODES REFERENCE (BY FUNCTION) Page ERROR CODES AND DIAGNOSTICS 6.1 ERROR RESPONSE CODES Page Page Page Page 6.2 PRIMITIVE ERRORS 6.3 MRSW TERMINATION CODES Page 6.4 DIAGNOSTIC TESTS Figure 61 Adapter LEDs Page Page LED Error Codes Figure 65 External I/O Loopback Test Connections APPENDIX A USING THE NON-INTELLIGENT TERMINAL PROTOCOL A.1 CHARACTERISTICS OF THE NONINTELLIGENT TERMINAL PROTOCOL : Figure A1 NITP Message Structure Table A1 NITP Character Set Page Page Page Page A.2 NITP Protocol Operation Page Page APPENDIX USING B THE BDLC PROTOCOL B.1 BDLC CONFIGURATION Figure B1 BDLC Unbalanced Configuration Page Table B1 BDLC Protocol Command Set Page B.3 BDLC PROTOCOL CONTROL FIELD STRUCTURES Figure B4 BDLC Protocol Control Field Structures Page B.4 COMMANDS AND RESPONSES Page B.5 ERRORS AND ERROR RECOVERY Page Figure B5 FRMR Information Field Format B.6 ILLUSTRATIVE BDLC SEQUENCES Page Page B.7 BLOCK CHECKSUM GENERATION AND CHECKING Page Page Page CONFIGURATION WORKSHEET Adapter Configuration Parameters Host Computer Port Parameters Network Ports Parameters APPENDIX F MACRO DEFINITIONS FORM MACRO DEFINITIONS FORM