Appendix B - RCS20 Remote Communications
Contents
1. Allow Spare Bytes Note These 6 bytes will repeat for channels 1 through 9 54 additional bytes used Opcode lt 2204h gt Set RCS20 Backup Mode Command Data Field 3 bytes Maximum Number of Backup Channels 2 for RCS20 Revision 1 6b August 17 2004 Page B 22 Appendix B Opcode lt 2205h gt Backup 1 Channel 0 Backup Mode Backup 2 Channel 9 Backup Mode RCS20 Remote Communications 0 Manual Automatic non Revertive 2 Automatic Revertive 0 Manual 1 Automatic non Revertive 2 Automatic Revertive will be ignored if Channel 9 is not configured as backup Clear RCS20 Latched Alarms There is no data field for this command Opcode lt 2206h gt Command Data Field 3 bytes Maximum Number of Backup Channels Backup 1 Channel 0 Channel to Backup Backup 2 Channel 9 Channel to Backup Force RCS20 Manual Backup 2 for RCS20 1 to 8 if Channel 9 configured as backup use 0 to un back 1 to 9 if Channel 9 not configured as backup use 0 to un back Bits 0 3 Modulator Bits 4 7 Demodulator 1 to 8 use 0 to un back Bits 0 3 Modulator Bits 4 7 Demodulator Notes 1 Command will return an error if Backup 1 and Backup 2 are forced to backup the same channel 2 Set channel 255 decimal if no forced backup is desired for either backup channel 3 Command will return an error if trying to force a backup for a backup channel not configured in2. August 17 2004 Page B 3 Appendix B RCS20 Remote Communications SPARM_DATACOUNT_ERROR 0201 Invalid number of data bytes SPARM_CHANNELNUM_ERROR 0202 Invalid number of M for N channels SPARM_CHANNELBYTES_ERROR 0203 Invalid number of bytes per channel SPARM_MODBACKUPDELAY_ERROR 020A Invalid modulator backup delay SPARM_DEMODBACKUPDELAY_ERROR 020B Invalid demodulator backup delay SPARM_BACKUPMODE_ ERROR 020C Backup channel 1 SPARM_CHANOCONFIG_ERROR 0213 Channel 0 Hardware Configuration SPARM_BACKUPCHANNEL_ ERROR 0214 Backup Channel SPARM_ MODEMNUMBER_ ERROR 0217 Invalid prime to backup SPARM_NOMODEMINSLOT_ERROR 0218 Prime is not present SPARM_BACKUP_NOT_PRESENT_ERROR 02B3 Backup is not present SPARM_BACKUP_IN_AUTO_MODE_ERROR 02B5 Backup is in automatic mode SPARM_MODEM9_IN_ TRAFFIC MODE ERROR 02B6 Modem is in traffic mode SPARM_MOD_AUTOBACKEDUP_ERROR 02BC Modulator is already auto backed up SPARM_DEMOD_AUTOBACKEDUP_ERROR 02BD Demodulator is already auto backed up SPARM_PRIME_IN SERVICE MODE ERROR 02BE Prime is in service mode SPARM_BACKUP_IN_SERVICE_MODE_ERROR 02BF Backup is in service mode SPARM_PRIME_BACKEDUP_TRAFFIC_ERROR 02C1 Prime backed up SPARM_PRIME_HS_TRAFFIC_ERROR 02C2 Is in Hot Standby SPARM_MODEM9_IN_BACKUP_MODE_ERROR 02C3 Modem is in backup mode SPARM_NOBACKUPASSIGNED_ERROR 02C5 No backups assigned for this mod SPARM_ MODEMNOTLEARNED_ ERROR 02C6 Modem is not learned
3. Backup 2 Channel 0 Force Manual Modulator Backup Backup 2 Channel 0 Force Manual Demodulator Backup Reserved Reserved Reserved Reserved Revision 1 6b August 17 2004 RCS20 Remote Communications 0 mask 1 allow Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 Mask 1 Allow 2 for RCS20 4 for RCS20 0 Backup modem 0 Manual Automatic non Revertive 2 Automatic Revertive Channel number for manual backup 1 to 9 ignored if in automatic mode Channel number for manual backup 1 to 9 ignored if in automatic mode 0 Backup modem 1 Preempt able prime modem 2 Prime Modem 0 Manual Automatic non Revertive 2 Automatic Revertive Channel number for manual backup 1 to 8 ignored if in automatic mode or if channel 9 is configured as prime Channel number for manual backup 1 to 8 ignored if in automatic mode or if channel 9 is configured as prime Reserved for RCS10 set to zero Reserved for RCS10 set to zero Reserved for RCS10 set to zero Reserved for RCS10 set to zero Page B 13 Appendix B RCS20 Remote Communications Reserved Reserved for RCS10 set to zero Learn Modem 0 Modem 0 1 Modem 1 2 Modem 2 3 Modem 3 4 Modem 4 5 Modem 5 6 Modem 6 7 Mode
4. IFS20 panels and are defined as follows Channel 0 Backup 1 Channel 1 Modem 1 Channel 2 Modem 2 Channel 3 Modem 3 Channel 4 Modem 4 Channel 5 Modem 5 Channel 6 Modem 6 Channel 7 Modem 7 Channel 8 Modem 8 Channel 9 Modem 9 Backup 2 RCS20 Switch Command Set Revision 1 6b August 17 2004 Page B 7 Appendix B RCS20 Remote Communications Command Opcode Description Command Switch Reference Distribution 2210h Set RCS20 RDM configuration Configuration Configuration Backup test all modem s configuration Configuration NOTE When new features are added to Radyne equipment the control parameters are appended to the end of the non volatile section and statuses of the features if any are added at the end of the volatile section If a remote M amp C queries two pieces of Radyne equipment with different revision software they might respond with two different sized packets The remote M amp C MUST make use of the non volatile count value to index to the start of the volatile section If the remote M amp C is not aware of the newly added features to the Radyne product it should disregard the parameters at the end of the non volatile section and index to the start of the volatile section If packets are handled in this fashion there will also be backward compatibility between Radyne equipment and M amp C systems Remote M amp C systems need not be modified every time a feature is added unless the user needs access
5. If the checksum values do not match the receiver replies with a negative acknowledgment NAK in its response frame The response packet is therefore either an acknowledgment that the message was received correctly or some form of a packetized NAK frame If the sender receives a valid acknowledgment response packet from the receiver the Revision 1 6b August 17 2004 Page B 6 Appendix B RCS20 Remote Communications lt FSN gt increments and the next packet is transmitted as required by the sender However if a NAK response packet is returned the sender re transmits the original information packet with the same embedded lt FSN gt If an acknowledgment response packet or a NAK packet is lost corrupted or not issued due to an error and is thereby not returned to the sender the sender re transmits the original information packet but with the same lt FSN gt When the intended receiver detects a duplicate packet the packet is acknowledged with a response packet and internally discarded to preclude undesired repetitive executions If the M amp C computer sends a command packet and the corresponding response packet is lost due to a system or internal error the computer times out and re transmits the same command packet with the same lt FSN gt to the same receiver and waits once again for an acknowledgment or a NAK packet To reiterate the format of the message block is shown in Table 4 Link Level Protocol Message Block SYNC COUNT S
6. Latched Switch Minor Alarms 1 Revision 1 6b August 17 2004 RCS20 Remote Communications performed 1 Mod backup 2 test pass 2 Mod backup 2 test fail Bits 6 and 7 Demod backup 2 test status 0 No Demod backup 2 test performed 1 Demod backup 2 test pass 2 Demod backup 2 test fail Notes These 3 bytes repeat for channels 1 9 5 bytes as of release 4 0 27 additional bytes 45 additional bytes as of release 4 0 Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup 1 Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Bit 6 Backup 2 Demod Error Bit 7 Spare 0 no alarm 1 alarm Bit 0 Power Supply 1 Present Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Bit 3 Power Supply 2 Voltage Bit 4 Communications Error Bit 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change 0 no alarm 1 alarm Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 no alarm 1 alarm Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup 1 Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Bit 6 Backup 2 Demod Error Bit 7 Spare 0 no al
7. SPARM_COPYDESTINATION_ ERROR 02CB Invalid copy destination B 1 5 Collision Avoidance When properly implemented the physical and logical devices and ID addressing scheme of the COMMSPEC normally precludes message packet contention on the control bus The importance of designating unique IDs for each device during station configuration cannot be overemphasized One pitfall which is often overlooked concerns multi drop override IDs All too often multiple devices of the same type are assigned in a direct linked single thread configuration accessible to the M amp C computer directly For example if two DMD15 Modems with different addresses DESTINATION IDs are linked to the same control bus at the same hierarchical level both will attempt to respond to the M amp C computer when the computer generates a multi drop override ID of 22 If their actual setup parameters status or internal timing differs they will both attempt to respond to the override simultaneously with different information or asynchronously in their respective message packets and response packets causing a collision on the serial control bus To preclude control bus data contention different IDs must always be assigned to the equipment If two or more devices are configured for direct linked operation then the M amp C computer and all other devices configured in the same manner must be programmed to inhibit broadcast of the corresponding multi drop override ID The multi
8. for which the message is to be relayed 0 to 9 for the RCS20 RLLP Packet from Complete addressed RLLP message block with variable number of Modem bytes sync byte source address destination address opcode byte count data field and checksum Contents of Response Packet Data Field Dependent upon message relayed to modem Opcode lt 2202h gt Set RCS20 Configuration Command Data Field Nonvolatile Bytes Number of nonvolatile RCS20 configuration memory bytes including these 2 bytes 221 decimal for RCS20 Number of Channels Maximum number of prime and backup channels available to the RCS20 switch 10 decimal for RCS20 as of Release 1 0 Nonvolatile Bytes per Number of nonvolatile memory bytes per channel This number may Channel vary with the release number 10 bytes for RCS20 as of release 1 0 Revision 1 6b August 17 2004 Page B 19 Channel 0 Configuration Channel 0 Mod Backup Delay Channel 0 Demod Backup Delay Channel 0 Mod Backup Configuration Channel 0 Demod Backup Configuration Channel 0 Mod Priority Channel 0 Demod Priority Channel 0 Switch Style Channel 0 Demod Acquisition Delay Service Mode Switch Major Alarm Mask Revision 1 6b August 17 2004 RCS20 Remote Communications and 13 bytes as of release 4 0 Remote M amp C developers must make use of this value to find out how many bytes per channel are being transmitted Bit 0
9. to 8 0 No hot standby for backup 2 mod or channel 9 not configured as backup Channel number 1 to 8 0 No hot standby for backup 2 Demod or Channel 9 not configured as backup Query RCS20 Modem Addresses Query Response Data Field 11 bytes Opcode lt 2004h gt Opcode lt 2005h gt Number of Channels Modem Address 0 Modem Address 1 Modem Address 2 Modem Address 3 Modem Address 4 Modem Address 5 Modem Address 6 Modem Address 7 Modem Address 8 Modem Address 9 Maximum Number of Backup Channels Backup 1 Channel 0 Backup Mode Backup 2 Channel 9 Backup Mode 10 for RCS20 Modem Remote Address for channel 0 BU 1 Modem Address 1 Modem Remote Address for channel Prime 1 Modem Address 2 Modem Remote Address for channel 2 Prime 2 Modem Address 3 Modem Remote Address for channel 3 Prime 3 Modem Address 4 Modem Remote Address for channel 4 Prime 4 Modem Address 5 Modem Remote Address for channel 5 Prime 5 Modem Address 6 Modem Remote Address for channel 6 Prime 6 Modem Address 7 Modem Remote Address for channel 7 Prime 7 Modem Address 8 Modem Remote Address for channel 8 Prime 8 Modem Address 9 Modem Remote Address for channel 9 Prime 9 BU 2 Query RCS20 Backup Mode Query Response Data Field 3 bytes 2 for RCS20 0 Manual 1 Automatic non Revertive 2 Automatic Revertive 0 Manual 1 Automatic non Revertive 2
10. to that feature OPCODE DESCRIPTIONS Opcode lt 2403h gt Query RCS20 Device Identification Query Response Data Field 1 Byte Device Identification 24 decimal for RCS20 Opcode lt 2404h gt Query RCS20 Switch Control Mode Query Response Data Field 1 Byte Revision 1 6b August 17 2004 Page B 8 Appendix B RCS20 Remote Communications Control Mode 0 Front Panel 1 Terminal Mode 2 Remote Port Opcode lt 2001h gt Query RCS20 Switch Status Query Response Data Field 44 bytes 64 bytes release 4 0 Control Mode Software Revision Number of Channels Number of Status Bytes Per Channel Channel 0 Status Backed up Modulator Backed up Demodulator Module 0 Alarms 2 Status Module 0 Alarms 3 Status Revision 1 6b August 17 2004 0 Front Panel 1 Terminal Mode 2 Remote Port Computer RLLP Binary number decimal point implied 10 decimal for RCS20 Maximum number of bytes per channel 3 as of release 1 0 5 as of release 4 0 This number of bytes per channel might change with newer release numbers It is set to 3 up to release 3 9 and 5 bytes as of release 4 0 Remote M amp C developers must make use of this value to find out how many bytes per channel are being transmitted Bit 0 modulator failure flag 0 no failure 1 failure Bit 1 demodulator failure flag 0 no failure 1 failure Bit 2 switch communication in process 0 no communicatio
11. 2 16h 00010110b The principal elements of a data frame in order of occurrence are summarized as follows lt SYNC gt the message format header character or ASCII sync character that defines the beginning of a message The lt SYNC gt character value is always 16h 1 byte lt BYTE COUNTS the Byte Count is the number of bytes in the lt DATA gt field 2 bytes lt SOURCE ID gt the Source Identifier defines the multi drop address origin Note that all nodes on a given control bus have a unique address that must be defined 1 byte lt DESTINATION ID gt the Destination Identifier serves as a pointer to the multi drop destination device that indicates where the message is to be sent 1 byte Revision 1 6b August 17 2004 Page B 1 Appendix B RCS20 Remote Communications lt FRAME SEQUENCE NUMBER the FSN is a tag with a value from 0 through 255 that is sent with each message It assures sequential information framing and correct equipment acknowledgment and data transfers 1 byte lt OPCODES the Operation Code field contains a number that identifies the message type associated with the data that follows it Equipment under MCS control recognizes these bytes via firmware identification and subsequently steers the DATA accordingly to perform a specific function or series of functions Acknowledgment and error codes are returned in this field 2 bytes lt DATA gt the Data field contains the binary b
12. Automatic Revertive Ignore if Channel 9 is not configured as backup Query RCS20 Expansion Module Information Query Response Data Field 7 bytes Number of Expansion Slots Slot 0 Expansion Type Revision 1 6b August 17 2004 6 for RCS20 255 decimal no expansion card present 0 RCS20 Interface Page B 17 Appendix B RCS20 Remote Communications Control Module 1 RCS20 Bank Control Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Slot 1 Expansion Type 255 decimal no expansion card present 0 RCS20 Interface Control Module 1 RCS20 Bank Control Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Slot 2 Expansion Type 255 decimal no expansion card present 0 RCS20 Interface Control Module 1 RCS20 Bank Control Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Slot 3 Expansion Type 255 decimal no expansion card present 0 RCS20 Interface Control Module 1 RCS20 Bank Control Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Slot 4 Expansion Type 255 decimal no expansion card present 0 RCS20 Interface Control Module 1 RCS20 Bank Control Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Slot 5 Expansion Type 255 decimal no expansion card present 0 RCS20 Interface Control Module 1 RCS20 Bank Contro
13. Modulator present Bit 1 Demodulator present 0 not present 1 present Oh BB7h in tenths of a second decimal point implied Oh BB7h in tenths of a second decimal point implied Bit 0 Backup 1 assigned to this modulator Bit 1 Backup 2 assigned to this modulator 0 not assigned assigned Bit 0 Backup 1 assigned to this demodulator Bit 1 Backup 2 assigned to this demodulator 0 not assigned 1 assigned Channel 0 Modulator backup priority 0 9 Channel 0 Demodulator backup priority 0 9 0 Switch Mod and Demod separately 1 Switch Mod and Demod together Oh BB7h in tenths of a second decimal point implied For example a value of 100 means 10 0 sec 0 Normal 1 Service NOTE These 10 bytes 13 bytes as of release 4 0 repeat for channels 1 9 uses 90 additional bytes uses 117 additional bytes as of release 4 0 NOTE The Backup Delays and Demod Acquisition Delay applies only to channels 1 9 the four channel 0 bytes are ignored If channel 9 is configured as backup 2 then the four channel 0 Backup Delay bytes and the two Demod Acquisition Delay bytes are ignored Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup 1 Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Page B 20 Switch Minor Alarm 1 Mask Switch Minor Alarm 2 Mask Maximum Number of Backup Channels Nonvolatile bytes per Ba
14. OURCE DESTINATION FSN OPCODE DATA BYTES CHECKSUM ADDRESS ADDRESS 1 BYTE 2BYTES 1 BYTE 1 BYTE 1 BYTE 2 BYTES COUNT BYTES 1 BYTE Table 4 Link Level Protocol Message Block B 2 Remote Port Packet Structure The RLLP Remote Port Packet structure is as follows lt SYNC gt Message format header character that defines the beginning of a message The lt SYNC gt character value is always 0x16 1 byte lt BYTE COUNT gt Number of bytes in the lt DATA gt field 2 bytes lt SOURCE ID gt Identifies the address of the equipment from where the message originated 1 byte lt DEST ID gt Identifies the address of the equipment where the message is to be sent 1 byte lt FSN gt Frame sequence number ensures correct packet acknowledgment and data transfers 1 byte lt OPCODE gt This byte identifies the message type associated with the information data The equipment processes the data according to the value in this field Return error codes and acknowledgment are also included in this field 2 bytes lt DATA gt Information data The number of data bytes in this field is indicated by the lt BYTE COUNTS value lt CHECKSUM gt The modulo 256 sum of all preceding message bytes excluding the lt SYNC gt character 1 byte RCS20 Channel Definitions The RCS20 organized the modems connected to the switch according to satellite communications channels These channels are labeled on the DDS20 and
15. RCS20 Remote Communications Specification TTT Appendix B Appendix B RCS20 Remote Communications B 1 Host Computer Remote Communications Control and status messages are conveyed between the RCS20 and the subsidiary modems and the host computer using packetized message blocks in accordance with a proprietary communications specification This communication is handled by the Radyne Link Level Protocol RLLP which serves as a protocol wrapper for the RM amp C data Complete information on monitor and control software is contained in the Radyne RLLP Protocol Reference Guide B 1 1 Protocol Structure The Communications Specification COMMSPEC defines the interaction of computer resident Monitor and Control software used in satellite earth station equipment such as modems redundancy switches multiplexers and other ancillary support gear Communication is bi directional and is normally established on one or more full duplex 9600 baud multi drop control buses that conform to EIA Standard RS 485 Each piece of earth station equipment on a control bus has a unique physical address which is assigned during station setup configuration or prior to shipment Valid decimal addresses on one control bus range from 32 through 255 for a total of up to 224 devices per bus Address 255 of each control bus is usually reserved for the M amp C computer B 1 2 Protocol Wrapper The Radyne COMMSPEC is byte oriented with the Least Significant Bit LSB issue
16. arm alarm Bit 0 Power Supply 1 Present Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Page B 10 Appendix B Latched Switch Minor Alarms 2 Backup 1 Mod Hot Standby Channel Backup 1 Demod Hot Standby Channel Backup 2 Mod Hot Standby Channel Backup 2 Demod Hot Standby Channel Opcode lt 2002h gt Query RCS20 Switch Confi RCS20 Remote Communications Bit 3 Power Supply 2 Voltage Bit 4 Communications Error Bit 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change 0 no alarm 1 alarm Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 no alarm 1 alarm Channel number 1 to 9 0 No hot standby for backup 1 mod Channel number 1 to 9 0 No hot standby for backup 1 Demod Channel number 1 to 8 0 No hot standby for backup 2 mod or channel 9 not configured as backup Channel number 1 to 8 0 No hot standby for backup 2 Demod or Channel 9 not configured as backup uration Query Response Data Field 285 bytes Configuration Bytes Nonvolatile Bytes Number of Channels Nonvolatile Bytes per Channel Channel 0 Configuration Channel 0 Mod Backup Delay Revision 1 6b August 17 2004 Number of nonvolatile RCS20 configurati
17. channel 9 is configured as prime Page B 21 Appendix B Backup 2 Channel 0 Force Manual Demodulator Backup Reserved Reserved Reserved Reserved Reserved Learned Modem Test Modem Additional Bytes per Channel Channel 0 Alarm 2 Mask Channel 0 Alarm 3 Mask Spares for Channel 0 RCS20 Remote Communications Channel number for manual backup 1 to 8 ignored if in automatic mode or if channel 9 is configured as prime Reserved for RCS10 set to zero Reserved for RCS10 set to zero Reserved for RCS10 set to zero Reserved for RCS10 set to zero Reserved for RCS10 set to zero 0 Modem 0 1 Modem 1 2 Modem 2 3 Modem 3 4 Modem 4 5 Modem 5 6 Modem 6 7 Modem 7 8 Modem 8 9 Modem 9 10 All Modems 0 Modem 1 1 Modem 2 2 Modem 3 3 Modem 4 4 Modem 5 5 Modem 6 6 Modem 7 7 Modem 8 8 Modem 9 9 All Modems 10 None Note This byte should be forced to 10 if no tests are desired failure to do so may result in momentary loss of link on selected modem s 6 bytes as of release 4 0 Bit 0 Mod learned Bit 1 Demod learned Bit 2 Mod configuration changed Bit 3 Demod configuration changed Bits 4 through 7 Spares 0 Mask 1 Allow Bits 0 and 1 Mod Backup 1 Test Status Mask Bits 2 and 3 Demod Backup 1 Test Status Mask Bits 4 and 5 Mod Backup 2 Test Status Mask Bits 6 and 7 Demod Backup 2 Test Status Mask 0 Mask 1
18. ckup Channel Backup 1 Channel 0 Configuration Backup 1 Channel 0 Backup Mode Backup 1 Channel 0 Force Manual Modulator Backup Backup 1 Channel 0 Force Manual Demodulator Backup Backup 2 Channel 9 Configuration Backup 2 Channel 9 Backup Mode Backup 2 Channel 0 Force Manual Modulator Backup Revision 1 6b August 17 2004 RCS20 Remote Communications Bit 6 Backup 2 Demod Error Bit 7 Spare 0 mask 1 allow Bit 0 Power Supply 1 Present Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Bit 3 Power Supply 2 Voltage Bit 4 Communications Error Bit 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change 0 mask 1 allow Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 Mask 1 Allow 2 for RCS20 4 for RCS20 0 Backup modem 0 Manual Automatic non Revertive 2 Automatic Revertive Channel number for manual backup 1 to 9 ignored if in automatic mode Channel number for manual backup 1 to 9 ignored if in automatic mode 0 Backup modem 1 Preempt able prime modem 2 Prime Modem 0 Manual Automatic non Revertive 2 Automatic Revertive Channel number for manual backup 1 to 8 ignored if in automatic mode or if
19. d and acknowledged as such If the command packet is received at its intended destination but the response message acknowledgment is lost then the message originator usually the M amp C computer re transmits the original command packet with the same FSN The destination device detects the same FSN and recognizes that the message is a duplicate so the associated commands within the packet are not executed a second time However the response packet is again sent back to the source as an acknowledgment in order to preclude undesired multiple executions of the same command To reiterate valid equipment responses to a message require the FSN tag in the command packet This serves as part of the handshake acknowledge routine If a valid response message is absent then the command is re transmitted with the same FSN For a repeat of the same command involving iterative processes the FSN is incremented after each message packet When the FSN value reaches 255 it overflows and begins again at zero The FSN tag is a powerful tool that assures sequential information framing and is especially useful where commands require more than one message packet The full handshake acknowledgment involves a reversal of source and destination ID codes in the next message frame followed by a response code in the lt OPCODE gt field of the message packet from the equipment under control If a command packet is sent and not received at its intended destination a timeout c
20. d and Demod together Oh BB7h in tenths of a second decimal point implied For example a value of 100 means 10 0 sec 0 Normal 1 Service NOTE These 10 bytes 13 bytes as of release 4 0 repeat for channels 1 9 uses 90 additional bytes uses 117 additional bytes as of release 4 0 NOTE The Backup Delays and Demod Acquisition Delay applies only to channels 1 9 the four channel 0 bytes are ignored If channel 9 is configured as backup 2 then the four channel 0 Backup Delay bytes and the two Demod Acquisition Delay bytes are ignored Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup 1 Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Bit 6 Backup 2 Demod Error Bit 7 Spare 0 mask 1 allow Bit 0 Power Supply 1 Present Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Bit 3 Power Supply 2 Voltage Bit 4 Communications Error Bit 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change Page B 12 Appendix B Switch Minor Alarm 2 Mask Maximum Number of Backup Channels Nonvolatile bytes per Backup Channel Backup 1 Channel 0 Configuration Backup 1 Channel 0 Backup Mode Backup 1 Channel 0 Force Manual Modulator Backup Backup 1 Channel 0 Force Manual Demodulator Backup Backup 2 Channel 9 Configuration Backup 2 Channel 9 Backup Mode
21. d first Each data byte is conveyed as mark space information with one mark comprising the stop data When the last byte of data is transmitted a hold comprises one steady mark the last stop bit To begin or resume data transfer a space 00h substitutes this mark This handling scheme is controlled by the hardware and is transparent to the user A pictorial representation of the data and its surrounding overhead may be shown as follows Sl S2 Bo B B2 B B4 B Be B Sl S2 etc The stop bits S1 and S2 are each a mark Data flow remains in a hold mode until S2 is replaced by a space If S2 is followed by a space it is considered a start bit for the data byte and not part of the actual data Bo B 7 The above byte oriented protocol is standard for UART based serial communication ports such as Workstation or Personal Computer PC COM ports COM ports should be configured for 8 data bits no parity and one stop bit For example for 9600 baud operation COM ports should be configured as 9600 8 N 1 The COMMSPEC developed for use with the Radyne Link Level Protocol RLLP organizes the actual monitor and control data within a shell or protocol wrapper that surrounds the data The format and structure of the COMMSPEC message exchanges are described herein Decimal numbers have no suffix hexadecimal numbers end with a lower case h suffix and binary values have a lower case b suffix Thus 2
22. dem 2 3 Modem 3 4 Modem 4 5 Modem 5 6 Modem 6 7 Modem 7 8 Modem 8 9 Modem 9 Modem configuration must be learned To Modem 0 Backup 1 1 Modem 1 2 Modem 2 3 Modem 3 4 Modem 4 5 Modem 5 6 Modem 6 7 Modem 7 8 Modem 8 9 Modem 9 10 All Modems Note The From and To modems must be present in the chassis and not equal to each other You can not copy a modem s configuration onto itself The Mod configuration will be copied and if successful the Demod configuration will be copied If any errors occur appropriate error Opcodes will be returned Opcode lt 2219h gt Backup Test Modem Configuration Command Data Field 1 byte lt 1 gt Modem Number 1 to 8 if channel 9 is configured as backup 1 to 9 if channel 9 is not configured as backup Opcode lt 221Ah gt Backup Test All Modem s Configurations There is no data field for this command Revision 1 6b August 17 2004 Page B 24 Appendix B RCS20 Remote Communications Note In order to backup test a modem configuration a modem must be a prime modem that has been assigned a backup The prime modem s configuration must be learned and its assigned backup present in the chassis Revision 1 6b August 17 2004 Page B 25 Appendix B RCS20 Remote Communications Revision 1 6b August 17 2004 Page B 1
23. drop override ID is always accepted by devices of the same type on a common control bus independent of the actual DESTINATION ID These override IDs with the exception of BROADCAST are responded to by all directly linked devices of the same type causing contention on the bus The BROADCAST ID on the other hand is accepted by all equipment but none of them returns a response packet to the remote M amp C The following multi drop override IDs are device type specific with the exception of BROADCAST These are summarized below with ID values expressed in decimal notation DIRECTLY ADDRESSED EQUIPMENT MULTI DROP OVERRIDE ID DMD 3000 4000 4500 or 5000 Mod Section DMDIS_ _ _ RCS 780 1 N Switch RMUX 340 Cross Connect Multiplexer CDS 780 Clock Distribution System fF 6 SES Revision 1 6b August 17 2004 Page B 4 Appendix B RCS20 Remote Communications SOM 340 Second Order Multiplexer DMD 4500 5000 Modulator Section DMD 4500 5000 Demodulator Section RCU 5000 M N Switch DMD15 Modulator DMD15 Demodulator Ee E DMD15 Modem DVB3000 D V B3030 DM45 Video Modulator RCS20 M N Switch RCS10 M N Switch RCS11 1 1 Switch DMD2401 VHS 101 VME2401 Modem Reserved for future equipment types 28 31 Table 3 Broadcast IDs 7 0 0 1 2 3 4 5 6 7 Note that multi drop override IDs 01 or 02 can be used interchangeably to broadcast a message to a DMD 3000 4000 modem or to a DMD 4500 5000 or to a DMD15 m
24. figuration has not changed 1 Demod configuration is changed Bits 4 through 7 Spares Bits 0 and 1 Mod backup 1 test status 0 No Mod backup 1 test performed 1 Mod backup 1 test pass 2 Mod backup 1 test fail Bits 2 and 3 Demod backup 1 test status 0 No Demod backup 1 test performed 1 Demod backup 1 test pass 2 Demod backup 1 test fail Bits 4 and 5 Mod backup 2 test status 0 No Mod backup 2 test performed 1 Mod backup 2 test pass 2 Mod backup 2 test fail Bits 6 and 7 Demod backup 2 test status 0 No Demod backup 2 test performed 1 Demod backup 2 test pass 2 Demod backup 2 test fail Notes These 3 bytes repeat for channels 1 9 5 bytes as of release 4 0 27 additional bytes 45 additional bytes as of release 4 0 Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup 1 Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Bit 6 Backup 2 Demod Error Bit 7 Spare 0 no alarm 1 alarm Bit 0 Power Supply 1 Present Page B 15 Switch Minor Alarms 2 Latched Switch Major Alarms Latched Switch Minor Alarms 1 Latched Switch Minor Alarms 2 Backup 1 Mod Hot Standby Channel Backup 1 Demod Hot Revision 1 6b August 17 2004 RCS20 Remote Communications Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Bit 3 Power Supply 2 Voltage Bit 4 Communications Error B
25. i directional data bytes associated with the command indicated by the lt Opcode gt field The number of bytes in this field is indicated by the lt B YTE COUNT gt value lt CHECKSUM gt the checksum is the modulo 256 sum of all preceding message bytes excluding the lt SYNC gt character 1 byte The checksum determines the presence or absence of errors within the message In a message block with the following parameters the checksum is computed as shown in Table 1 BYTE FIELD DATA CONTENT RUNNING CHECKSUM Table 1 Checksum Calculation Example Thus the checksum is 00000101b which is 05h or 5 decimal Alternative methods of calculating the checksum for the same message frame are 00h 02h FOh 2Ah 09h 00 03h DFh FEh 305h Since the only concern is the modulo 256 modulo 1 00h equivalent values that can be represented by a single 8 bit byte the checksum is O5h For a decimal checksum calculation the equivalent values for each information field are 0 2 240 42 9 3 4223 254 773 773 256 3 with a remainder of 5 This remainder is the checksum for the frame 5 decimal 05h 0101b lt CHECKSUM gt B 1 3 Frame Description and Bus Handshaking In a Monitor and Control environment every message frame on a control bus port executes as a packet in a loop beginning with a wait for SYNC character mode The remaining message format header information is then loaded either by the M amp C computer
26. it 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change 0 no alarm 1 alarm Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 no alarm 1 alarm Bit 0 RAM ROM fault Bit 1 No Backup for Faulted Prime Bit 2 Error During Backup Bit 3 Backup Mod Error Bit 4 Backup 1 Demod Error Bit 5 Backup 2 Mod Error Bit 6 Backup 2 Demod Error Bit 7 Spare 0 no alarm alarm Bit 0 Power Supply 1 Present Bit 1 Power Supply 1 Voltage Bit 2 Power Supply 2 Present Bit 3 Power Supply 2 Voltage Bit 4 Communications Error Bit 5 Faulted Prime Modem Bit 6 Faulted Backup Modem Bit 7 Modem Configuration Change 0 no alarm 1 alarm Bit 0 CDM Error Bit 1 Reserved RCS10 only Bit 2 Reserved RCS10 only Bit 3 Reserved RCS10 only Bit 4 Backup 1 Test Fault Bit 5 Backup 2 Test Fault Bit 6 Reserved RCS10 only Bit 7 Spare 0 no alarm 1 alarm Channel number 1 to 9 0 No hot standby for backup 1 mod Channel number 1 to 9 0 No hot standby for backup 1 Demod Page B 16 Appendix B Opcode lt 2003h gt Standby Channel Backup 2 Mod Hot Standby Channel Backup 2 Demod Hot Standby Channel RCS20 Remote Communications Channel number 1
27. l Module 2 RCS20 Ethernet Interface Module 3 RCS20 Reference Distribution Module Opcode lt 2010h gt Query RCS20 Reference Distribution Module Configuration Command Data Field 1 byte lt l gt RDM Slot Number Slot number on the RCU20 for the RDM to be queried Query Response Data Field 4 bytes RDM Status Bit 0 Ext A Activity Bit 1 Ext B Activity Bit 2 Internal Ref Activity RDM Fallback 0 External A Only 1 Internal Only 2 Ext A gt Int 3 Int gt Selection Ext A 4 Ext A gt Ext B 5 Ext A gt Ext B gt Int 6 Int gt Ext A gt Ext B RDM Internal 0 10 MHz 1 5 MHz 2 2 5 MHz 3 1 25 MHz Reference Frequency RDM Currently 0 External A 1 External B 2 Internal Selected Source Opcode lt 240Eh gt Query Time Query Response Revision 1 6b August 17 2004 Page B 18 Appendix B RCS20 Remote Communications lt I gt Minute lt l gt Second Opcode lt 240Fh gt Query Date Query Response lt I gt Year 0 99 lt I gt Month 0 11 lt l gt Day 0 30 Opcode lt 2410h gt Query Time and Date Query Response Hour Minute Second Opcode lt 2600h gt Set RCS20 Switch Control Mode Command Data Field 1 byte Control Mode 0 Front Panel 1 Terminal 2 Remote Port Computer RLLP Opcode lt 2200h gt Relay Command or Query to Modem Command Data Field n 1 bytes Channel Number Channel number for the modem
28. m 7 8 Modem 8 9 Modem 9 10 All Modems Test Modem 0 Modem 1 1 Modem 2 2 Modem 3 3 Modem 4 4 Modem 5 5 Modem 6 6 Modem 7 7 Modem 8 8 Modem 9 9 All Modems 10 None Note This byte should be forced to 10 if no tests are desired failure to do so may result in momentary loss of link on selected modem s Additional Bytes per 6 bytes as of release 4 0 Channel Channel 0 Alarm 2 Bit 0 Mod learned Mask Bit 1 Demod learned Bit 2 Mod configuration changed Bit 3 Demod configuration changed Bits 4 through 7 Spares 0 Mask 1 Allow Channel 0 Alarm 3 Bits 0 and 1 Mod Backup 1 Test Status Mask Mask Bits 2 and 3 Demod Backup 1 Test Status Mask Bits 4 and 5 Mod Backup 2 Test Status Mask Bits 6 and 7 Demod Backup 2 Test Status Mask 0 Mask 1 Allow Spares for Channel 0 Spare Bytes Note These 6 bytes will repeat for channels 1 through 9 54 additional bytes used Status Bytes Control Mode 0 Front Panel 1 Terminal Mode 2 Remote Port Computer RLLP Software Revision Binary number decimal point implied Number of Channels 10 decimal for RCS20 Number of Status Bytes Maximum number of bytes per channel 3 as of release 1 0 5 as of Per Channel release 4 0 This number of bytes per channel might change with newer release numbers It is set to 3 up to release 3 9 and 5 bytes as of release 4 0 Remote M amp C developers must make use of this value
29. manual backup mode Opcode lt 2210h gt Set RCS20 Frequency Distribution Module Configuration Command Data Field 3 bytes Opcode lt 2C04h gt Opcode lt 2C05h gt lt I gt RDM Slot Number RDM Fallback Mode RDM Internal Reference Frequency Hour Minute Second Year Revision 1 6b August 17 2004 Slot number on the RCU20 for the RDM to be configured 0 External A Only 1 Internal Only 2 Ext A gt Int 3 Int gt Ext A 4 Ext A gt Ext B 5 Ext A gt Ext B gt Int 6 Int gt Ext A gt Ext B 0 10 MHz 1 5 MHz 2 2 5 MHz 3 1 25 MHz Command Set Time Command Set Date 0 99 Page B 23 Appendix B RCS20 Remote Communications Opcode lt 2C06h gt Command Set Date and Time Year Month Day Hour Minute Second Opcode lt 2216h gt Learn Modem Configuration Command Data Field 1 byte lt l gt Modem Number 0 Modem 0 1 Modem 1 2 Modem 2 3 Modem 3 4 Modem 4 5 Modem 5 6 Modem 6 7 Modem 7 8 Modem 8 9 Modem 9 Opcode lt 2217h gt Learn All Modem s Configurations There is no data field for this opcode Note In order to learn a modem s configuration a modem must be a backup modem or a prime modem that has been assigned a backup The modem must be present in the chassis Opcode lt 2218h gt Copy Modem Configuration Command Data Field 2 bytes From Modem 0 Modem 0 1 Modem 1 2 Mo
30. n in process communication in process Bit 3 modem communication fault 0 no failure 1 failure Bit 4 modulator present 0 not present 1 present Bit 5 demodulator present 0 not present 1 present 0 This channel not a backup channel or this channel is a backup channel but currently not backing up a mod 1 9 This channel currently backing up a mod channel number as indicated 0 This channel not a backup channel or this channel is a backup channel but currently not backing up a demod 1 9 This channel currently backing up a demod channel number as indicated Bit 0 Mod learned 0 Mod is not learned 1 Mod is learned Bit 1 Demod learned 0 Demod is not learned 1 Demod is learned Bit 2 Mod configuration changed 0 Mod configuration has not changed 1 Mod configuration is changed Bit 3 Demod configuration changed 0 Demod configuration has not changed 1 Demod configuration is changed Bits 4 through 7 Spares Bits 0 and 1 Mod backup 1 test status 0 No Mod backup 1 test performed 1 Mod backup 1 test pass 2 Mod backup 1 test fail Bits 2 and 3 Demod backup 1 test status 0 No Demod backup 1 test performed 1 Demod backup 1 test pass 2 Demod backup 1 test fail Bits 4 and 5 Mod backup 2 test status 0 No Mod backup 2 test Page B 9 Appendix B Switch Major Alarms Switch Minor Alarms 1 Switch Minor Alarms 2 Latched Switch Major Alarms
31. n of setting a timeout on the incoming message Thus if the equipment does not receive an information command packet within a given time period the associated RLLT exits the I O wait state and takes appropriate action Radyne equipment is logically linked to the control bus via an Internal I O Processing Task IOPT to handle frame sequencing error checking and handshaking The IOPT is essentially a link between the equipment RLLT and the control bus Each time the M amp C computer sends a message packet the IOPT receives the message and performs error checking If errors are absent the IOPT passes the message to the equipment s RLLT If the IOPT detects errors it appends error messages to the packet Whenever an error occurs the IOPT notes it and discards the message but it keeps track of the incoming packet Once the packet is complete the IOPT conveys the appropriate message to the RLLT and invokes an I O wait state wait for next lt SYNC gt character If the RLLT receives the packetized message from the sender before it times out it checks for any error messages appended by the IOPT In the absence of errors the RLLT processes the received command sent via the transmitted packet and issues a message out system call to ultimately acknowledge the received packet This call generates the response packet conveyed to the sender If the IOPT sensed errors in the received packet and an RLLT timeout has not occurred the RLLT causes the equipment
32. nnot be attained by other means When Radyne equipment is queried for information Query Mod Query Demod etc it responds by sending back two blocks of data a non volatile section parameters that can be modified by the user and a volatile section status information It also returns a count value that indicates how large the non volatile section is M amp C developers to index into the start of the volatile section use this count When new features are added to Radyne equipment the control parameters are appended to the end of the non volatile section and status of the features if any are added at the end of the volatile section If a remote M amp C queries two pieces of Radyne equipment with different revision software they might respond with two different sized packets The remote M amp C MUST make use of the non volatile count value to index to the start of the volatile section If the remote M amp C is not aware of the newly added features to the Radyne product it should disregard the parameters at the end of the non volatile section and index to the start of the volatile section Revision 1 6b August 17 2004 Page B 5 Appendix B RCS20 Remote Communications If packets are handled in this fashion there will also be backward compatibility between Radyne equipment and M amp C systems Remote M amp C systems need not be modified every time a feature is added unless the user needs access to that feature B 1 7 Flow Control and Task P
33. odem Radyne Corp recommends that the multi drop override IDs be issued only during system configuration as a bus test tool by experienced programmers and that they not be included in run time software It is also advantageous to consider the use of multiple bus systems where warranted by a moderate to large equipment complement Therefore if an RCS20 switch is queried for its equipment type identifier it will return a 24 B 1 6 Software Compatibility A CAUTION The RCS20 RLLP is not software compatible with the following previous Radyne products RCU5000 and DMD4500 These products may not occupy the same bus while using this protocol as equipment malfunction and loss of data may occur The COMMSPEC operating in conjunction within the RLLP shell provides for full forward and backward software compatibility independent of the software version in use New features are appended to the end of the DATA field without OPCODE changes Older software simply discards the data as extraneous information without functional impairment for backward compatibility If new device resident or M amp C software receives a message related to an old software version new information and processes are not damaged or affected by the omission of data The implementation of forward and backward software compatibility often but not always requires the addition of new Opcodes Each new function requires a new Opcode assignment if forward and backward compatibility ca
34. on memory bytes including these 2 bytes 221 decimal for RCS20 Maximum number of prime and backup channels available to the RCS20 switch 10 decimal for RCS20 as of Release 1 0 Number of nonvolatile memory bytes per channel This number may vary with the release number 10 bytes for RCS20 as of release 1 0 and 13 bytes as of release 4 0 Remote M amp C developers must make use of this value to find out how many bytes per channel are being transmitted Bit 0 Modulator present Bit 1 Demodulator present 0 not present 1 present Oh BB7h in tenths of a second decimal point implied Page B 11 Channel 0 Demod Backup Delay Channel 0 Mod Backup Configuration Channel 0 Demod Backup Configuration Channel 0 Mod Priority Channel 0 Demod Priority Channel 0 Switch Style Channel 0 Demod Acquisition Delay Channel 0 Service Mode Switch Major Alarm Mask Switch Minor Alarm 1 Mask Revision 1 6b August 17 2004 RCS20 Remote Communications Oh BB7h in tenths of a second decimal point implied Bit 0 Backup 1 assigned to this modulator Bit 1 Backup 2 assigned to this modulator 0 not assigned 1 assigned Bit 0 Backup 1 assigned to this demodulator Bit 1 Backup 2 assigned to this demodulator 0 not assigned assigned Channel 0 Modulator backup priority 0 9 Channel 0 Demodulator backup priority 0 9 0 Switch Mod and Demod separately 1 Switch Mo
35. ondition can occur because the packet originator does not receive a response message On receiving devices slaved to an M amp C computer the timeout delay parameters may be programmed into the equipment in accordance with site requirements by Radyne Corp prior to shipment or altered by qualified personnel The FSN handshake routines must account for timeout delays and be able to introduce them as well B 1 4 Global Response Operational Codes In acknowledgment response packets the operational code lt OPCODE gt field of the message packet is set to 0 by the receiving devices when the message intended for the device is evaluated as valid The device that receives the valid message then exchanges the lt SOURCE ID gt with the lt DESTINATION ID gt sets the lt OPCODE gt to zero in order to indicate that a good message was received and returns the packet to the originator This GOOD MESSAGE opcode is one of nine global responses Global response opcodes are common responses issued to the M amp C computer or to another device that can originate from and are interpreted by all Radyne equipment in the same manner These are summarized as follows all opcode values are expressed in decimal form PRADA KONNI DKO 100 D DM D INIO t 1 a N CON 0 00 D0 Table 2 Response Opcodes The following response error codes are specific to the RCS20 RCS20 RESPONSE ERROR CODES DESCRIPTION OPCODE DESCRIPTION Revision 1 6b
36. or by a subordinate piece of equipment such as the RCS20 requesting access to the bus Data is processed in accordance with the OPCODE and the checksum for the frame is calculated If the anticipated checksum does not match then a checksum error response is returned to the message frame originator The entire message frame is discarded and the wait for SYNC mode goes back into effect If the OPCODE resides within a command message it defines the class of action that denotes an instruction which is specific to the device type and is a Revision 1 6b August 17 2004 Page B 2 Appendix B RCS20 Remote Communications prefix to the DATA field if data is required If the OPCODE resides within a query message packet then it defines the query code and can serve as a prefix to query code DATA The Frame Sequence Number FSN is included in every message packet and increments sequentially When the M amp C computer or bus linked equipment initiates a message it assigns the FSN as a tag for error control and handshaking A different FSN is produced for each new message from the FSN originator to a specific device on the control bus If a command packet is sent and not received at its intended destination then an appropriate response message is not received by the packet originator The original command packet is then re transmitted with the same FSN If the repeated message is received correctly at this point it is considered a new message and is execute
37. rocessing The original packet sender the M amp C computer relies on accurate timeout information with regard to each piece of equipment under its control This provides for efficient bus communication without unnecessary handshake overhead timing One critical value is designated the Inter Frame Space FS The Inter Frame Space provides a period of time in which the packet receiver and medium control bus and M amp C computer interface fully recover from the packet transmission reception process and the receiver is ready to accept a new message The programmed value of the Inter Frame Space should be greater than the sum of the turnaround time and the round trip sender receiver bus propagation time including handshake overhead The term turnaround time refers to the amount of time required for a receiver to be re enabled and ready to receive a packet after having just received a packet In flow control programming the Inter Frame Space may be determined empirically in accord with the system configuration or calculated based on established maximum equipment task processing times Each piece of supported equipment on the control bus executes a Radyne Link Level Task RLLT in accordance with its internal hardware and fixed program structure In a flow control example the RLLT issues an internal message in system call to invoke an I O wait condition that persists until the task receives a command from the M amp C computer The RLLT has the optio
38. to find out how many bytes per channel are being transmitted Revision 1 6b August 17 2004 Page B 14 Appendix B Channel 0 Status Backed up Modulator Backed up Demodulator Module 0 Alarms 2 Status Module 0 Alarms 3 Status Switch Major Alarms Switch Minor Alarms 1 Revision 1 6b August 17 2004 RCS20 Remote Communications Bit 0 modulator failure flag 0 no failure 1 failure Bit 1 demodulator failure flag 0 no failure 1 failure Bit 2 switch communication in process 0 no communication in process communication in process Bit 3 modem communication fault 0 no failure 1 failure Bit 4 modulator present 0 not present 1 present Bit 5 demodulator present 0 not present 1 present 0 This channel not a backup channel or this channel is a backup channel but currently not backing up a mod 1 9 This channel currently backing up a mod channel number as indicated 0 This channel not a backup channel or this channel is a backup channel but currently not backing up a demod 1 9 This channel currently backing up a demod channel number as indicated Bit 0 Mod learned 0 Mod is not learned 1 Mod is learned Bit 1 Demod learned 0 Demod is not learned 1 Demod is learned Bit 2 Mod configuration changed 0 Mod configuration has not changed 1 Mod configuration is changed Bit 3 Demod configuration changed 0 Demod con
39. to issue the appropriate error message s in the pending equipment response frame To maintain frame synchronization the IOPT keeps track of error laden packets and packets intended for other equipment for the duration of each received packet Once the packet is complete the IOPT invokes an I O wait state and searches for the next lt SYNC gt character NOTE When transmitting a packet the Remote M amp C should ensure that the timeout value between characters does not exceed the time it takes to transmit 200 characters 200 msec If this timeout value is exceeded the equipment will timeout B 1 8 RLLP Summary The RLLP is a simple send and wait protocol that automatically re transmits a packet whenever an error is detected or when an acknowledgment response packet is absent During transmission the protocol wrapper surrounds the actual data to form information packets Each transmitted packet is subject to timeout and frame sequence control parameters after which the packet sender waits for the receiver to convey its response Once a receiver verifies that a packet sent to it is in the correct sequence relative to the previously received packet it computes a local checksum on all information within the packet excluding the lt SYNC gt character and the lt CHECKSUMs gt fields If this checksum matches the packet lt CHECKSUMS the receiver processes the packet and responds to the packet sender with a valid response acknowledgment packet
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