Class Note for ECE 493 at UA-Spec Topics Optics
Class Note for ECE 493 at UA-Spec Topics Optics
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This 6 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Alabama - Tuscaloosa taught by a professor in Fall. Since its upload, it has received 28 views.
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Date Created: 02/06/15
Communlcations Instructlons Programmable Logic Controllers Communications and Communications Instructions The communication instructions read or write data to another station Instruction Used To MSG Transfer data frnrn Dne device to another SVC interrupt the pragiarn scan U execute the service cuiiirnu nications part of the operating cycie The scan then iesuines atthe instruction fuiioWiiig the SVC instruction Communlcatlons Instructions Messaglng OverVIew 0 Two communications instructions e Message MSG and e Service communications svc We will look at e how messaging works e what the instructions look like e how to configure and use the instructions e examples and timing diagrams The communication when scanned the message architecture is comprised of and the data defined Wlthln three primary components the message if t is a write 7 Ladder Scan message are placed in a communication buffer mm mm Buffers The controller continues to T C mmun canon Queue scan the remaining user These three component program determine when a message The message 5 processed is transmitted by the and sent out of the controller controller Via the communications port after the ladder logic completes during the Servlce Communications part of the operating cycle unless an svc is executed For a message to transmit it must be scanned on a true rung of logic Messaging Overview continued o If a second message instruction is processed before the first message completes the second message and its data are placed in one of the three remaining communication buffers o This process repeats whenever a message instruction is processed until all four buffers are in use Eieetneei a Computer Engineering Dr D J Jackson Lemure 12 5 Messaging Overview continued 0 When a message request in a buffer is completed the buffer is released back to the system 0 If a message is in the queue that message is then allocated a buffer 0 At that time the data associated with the message is read from within the controller 0 The buffer and queue mechanisms are completely automatic Buffers are allocated and released as the need arises and message queuing occurs if buffers are full 0 If a message instruction was in the queue the data that is actually sent out of the controller may be different than what was present when the message instruction was first processed Eieetrreei a Computer Engineering Dr D J Jackson Lecture 12 7 Messaging Overview continued 0 When a buffer is available the message and its associated data are placed in the buffer immediately 0 If all four buffers for the channel are full when the next fifth message is processed the message request not the data is placed in the channel39s communications queue o The queue is a message storage area that keeps track of messages that have not been allocated a buffer 0 The queue operates as a first in first out FIFO storage area a The rst message request stored in the queue is the message that is allocated a buffer as soon as a buffer becomes available 0 The queue can accommodate all MSG instructions in a ladder program MSG Message Eieetneei a Computer Engineering Dr D J Jackson Lemure 12 s 0 Any preceding logic on the M35 message rung must be ReadWrite Messaqe EN solved true before the w v 39 39 truction can be MSG Hie M8910 DN message ms processed The example semi SUBS ER below shows a message instruction I BSUi SG 1 E KeadJWnte Mesgzge ltENgt MSG File MGQD 1DN Setup Semen 1gtSs Eieetrreei a Computer Engineering Dr D J Jackson Lecture 12 s The Message File Creating a Message File 1 unlllled HE E a om Flles A Cmss Relevance omouwm I ll warm I szrsYAms IE ELEMARV NJlMER I CSVCOUNYER B Rsmmwot IE NLMEGER I VEVRESERVED a 45 Fan la ourouwm El l1 warm 3 g Custom Data Mannms IE com u ummeu f The MSG instmction built into the controller uses a MG data file to process the message instmction The MG data file shown at left is accessed using the MG prefix Each message instmction utilizs an element within a MG data file For example MG90 is the first element in message data file 9 NOTE This message data file may need to be created 0 Select a File Number 9 in this example 0 Select a File Type Message 0 Select a File Name MESSAGE in this example 0 Select the number of elements for the data file 10 in this example quot1 Wm N ml m aquot if a r as r Suva whim um am e m c m 3 z lmnul x cannula Enunmll m ELIclam Lamile a z lmnul x Carmina Enunml39 nrnJJclmn Lamile 11 Creating a Message File Local Messages 0 With the Data Files selected right click and select New39 0 After the MESSAGE data file is created the properties of the data file can be modified Pmpatles I 535mm m wrle E CSVOOUNTER I yrscomm IE NMNVEGER imam p g Fume Flles Ia ououwu7 E n wam t g Cuslnm m Monkeys IE cm a Unmled o The controller is capable of communicating using local or remote messages 0 With a local message all devices are accessible without a separate device acting as a bridge 0 Different types of electrical interfaces may be required to connect to the network but the network is still classified as a local network 0 Remote messages use a remote network where devices are accessible only by passing or routing through a device to another network 0 All of our message types will be local z lmnul x cannula Enunmll m ELIclam Lamile 1n z lmnul x Carmina Enunml39 nrnJJclmn Lamile 12 Local DH485 Network with AIC 1761NETAIC Interface an m Mexwml RSLogix Message Setup Screen 0 The RSLogix Mssage Setup Screen is shown below This screen is used to enter the setup elemenls for This Oontrollerquot Target Devicequot and Control Bilsquot Elumczl emanertneneenre D D J chleon mm 1213 Hemmer 5 Emmy Ergnee rg or D J chksm tom 2 15 Configuring a Local Message 0 Message Setup Screen e Tne rung below snows e MSG mstructron preoeded pv oondrtroner ogrc Access dne messege setup soeen pv doublenchd ng Setup Screen mm film wwmdreeee 4 merge MGBEI 4CD 42x Semi screen This Controller Parameters 0 Communication Command e Tne controHer supports srx drrrerent tvpes or oom mumoetrons commends it tne terget devroe supports anv or tnese commend tvpes tne controHer should be capable of exdnengmg dete wrtn tne devrce Supported commends mclude um Elumczl emanertneneenre D D J chleon udumzu Hemmer 5 Emmy Ergnee rg or D J chksm Ledue121s Data Table Address Thts yartabte de nes the starttng address tn the tocat controtter yattd ttte types tor the Data Tabte Address are shown betovy Mcss ue ma Mnssnuu WIN atrtat ttttttttattt that ttt tttttttt tt t ttttttt ttt ttttttnt tttttttst tttt tttttttte tt t tttttathttttttt tmtttttttttt tttrtttt tttt tattta tnttttt ttt Stttto tsntvtt ttt tt ttttttttt ttttttt MaXImum Data Transferred By An MSG Instruct39on MessayeTvpe FlleT le EtematttStze Matt tNttttttat n Unmmls m Mcssanc tenet u t t tt t wtd tUE t 2mm 5t t t h Jtmrd 3a 5t 4 twttt zttrtttta attttt sown u t t tt t wtd tUE L mam 5t t t H 3 t tt 34 Mt tttttott t we Dttttt m u t t tt t t tt ta L Mott 5t t 5 t tt 39 stutttttaoattpurtnatttrttta a at that than a tt autttttaoatpuar atattttttta a at quotthat than a t Size in Elements Ta rg et Devi cequot Pa ra m ete rs Thts yartabte det tnes the amount of data tt t etemene to exchange thh the target devtce The rnaxtrnurn amount of data that can be transferred Vta a MSG tnstrucuon ts 103 Words 205 bytes and ts determtned by the destination data type The desunauon data type ts de ned by the type of message read or Wnte 7 Fur Read Messages When a read message ts used the desttnattnn ftte ts the data ftte tn the tncat Dr Drtgtnattng Dracessnr tnaut autaut strtna aha RTc te types are nat yattd rar read messages 7 Fur Wrte Messages When a Wrtte message ts used the desttnattnn ftte ts the data ftte tn the targ t Drncessnr you cannot cross te types when sendtng messages For exampte you cannot read a ttmer tnto an tnteger te and you cannot Wt tte counters to a ttmer te Message Timeout a Thts yatue de nes how tong tn seconds the message tnstmcuon has to comptete tts operauon once tt has started a 39 rntng begtns when the fatsertoru39ue rung transtuon occurs enabttng the message Ifthe umeoutpenod exptres the message errors out The defauttvatue tss seconds The rnaxtrnurn umeout yatue ts 255 seconds a If the message ttmeoutts set to zero the message tnstrucuon tht never umeout Set the rne out bttTo 1 to ush a message tnstrucuon from tts buffer tfthe desttnatton devtce does not respond to the communtcattons request stutttttaoattpurtnatttrttta a at that than a tt autttttaoatpuar atattttttta a at quotthat than a at Data Table AddressOffset o This variable defines the starting address in the target controller The data table address is used for a SOOCPU and PLCS type messages 0 A valid address is any valid configured data file within the target device whose file type is recognized by the controller Valid combinations are shown below Message Type Local File Type Target File Type 5D an J T T C C R R Rm ll N RTC 1 snucvu wille RTCrtnrilllegel ulRTCrlurRTC ulliy Appiles 1e lllrmulegrx lean 17mm Selles a and 17mm Plucessms mli Eleclnczl a Cnmrluler Ennlneennu Dr D l Jacksnn lecture 12 21 Local Node Address o This is the destination device39s node number if the devices are on a DH 485 using l761 NET AIC DeviceNet using l761 NET DNI or DF1 Half Duplex network To initiate a broadcast message on a DH485 network set the local node address to 1 o LocalRemote This variable defines the type of communications that is used Use oca when you need pointtopoint communications via DF1 FullDuplex or network communications such as DH485 using 1761NETAIC DeviceNet using 1761NETDNI or DF1 HalfDuplex 0 NOTE ALL OUR COMMUNICATIONS WILL BE LOCAL Eleclnczl a Cnmrluler Ennlneennu Dr D l Jacksnn lecture 12 22
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