1747-6.15-DU1
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1. DID and I O Interrupt OD Entry Time SLC 5 03 Processors SLC 5 04 Processors STI 425 us 355 us Dil 440 us 365 us 101 715 us 595 us Interfacing with Enhanced Bar Code Decoders Over DH 485 Network Using the MSG Instruction SLC 5 03 and SLC 5 04 Operating Systems 5 The purpose of this section is to illustrate how to interface Allen Bradley Enhanced Bar Code Decoders to SLC 5 03 and 5 04 processors via the DH 485 network Enhanced Bar Code Decoders act only as slave devices on this network This means that these decoders cannot initiate the transfer of data to a host device such as the SLC 5 03 or SLC 5 04 processor on DH 485 The SLC processor must initiate commands to a decoder and poll that decoder for the reply to those commands Processor and Decoder Operation The Enhanced Bar Code Decoder catalog number 2755 DS DD Series B when used as a node on a DH 485 network can act as a slave only This means that the decoder may not initiate communications to any other node on the network Therefore in order for a device to get bar code data from an Enhanced Bar Code Decoder on a DH 485 network that device must send a read command and then poll the decoder for the reply with data The only devices capable of polling a slave device on DH 485 are the SLC 5 03 and 5 04 processors For the SLC 5 03 processors 1747 08302 FRN10 or later polling can be done via channels 0 and 1 For the SLC2. 1 E 12 END Publication 1747 6 15 DU1 May 1997 4 SLC 5 03 and SLC 5 04 Operating Systems Day of Week with Real Time Clock Interrupt Latency Publication 1747 6 15 DU1 May 1997 The SLC 5 03 1747 OS302 FRN10 and SLC 5 04 1747 0S401 FRN7 processors now support the Day of Week feature as part of the Real Time Clock Although this feature is not yet supported by programming software you can access Day of Week via ladder programming The Day of Week status word must be initialized Initialization is done by setting the year month and date in the system status file The status words for setting these values are Calendar Status Words Status Word Valid Range Year 37 0 65535 Month 38 1 12 January 1 Date 39 1 31 first day of month 1 Once the date has been set the processor determines the Day of Week and writes it to 53 S 53 is read only and non volatile Interpret the Day of Week values as shown below Day of Week Integer Values Sunday Monday Tuesday Wednesday Thursday Friday Saturday 0 1 2 3 4 5 6 Note If the status of word S 53 is not properly initialized it will contain a random value There are new interrupt latency specifications for the SLC 5 03 1747 OS302 FRN10 and SLC 5 04 1747 OS401 FRN7 processors Use the values shown below for calculating interrupt latency for Selectable Timed Interrupt STI Discrete Input Interrupt
3. 5 04 processors 1747 OS401 FRN7 or later channel 0 supports this capability There are many ways to trigger bar code decoders to read a bar code label when a label is present e a package detect switch wired to both an SLC input module and the bar code decoder e a package detect switch wired only to an SLC input and an SLC output then used to trigger the decoder e via a software trigger command from the SLC processor For this example the software trigger is used However the basic principal is the same for all trigger modes Publication 1747 6 15 DU1 May 1997 SLC 5 03 and SLC 5 04 Operating Systems Publication 1747 6 15 DU1 May 1997 System Set Up In this example a photo switch is located such that when it detects a product is in position for the bar code scanner to read a bar code label on the product a discrete input to the SLC 5 03 processor is energized SLC i O 1747 Chassis OSER R Pe E DH F Power Supply i 1747 AIC Host Port mnm nmr 2755 DS DD A Enhanced Bar or Code Decoder n h The 5 03 ladder program then initiates a MSG Write to the decoder to trigger the decoder to start scanning for a valid bar code label When the decoder is scanning for a valid bar code lab
4. Bit N7 0 N7 0 1 U 12 15 This rung detects false to true transitions of either a good read or a no read input from the bar code decoder and latches internal storage bit B3 2 B3 2 will then in the next rung initialize the MSG read command to the decoder This is done if either a good read or a no read occurs because the no read message configured in the decoder is data as much as actual bar code label data Therefore the ladder program must distinguish between data that means no read as well as actual bar code label data Good Read Input from Bar Code Decoder I 1 B3 0 B3 0 E OSR L 1 3 2 1746 1I1 16 No Read Input from Bar Code Decoder I 1 E 2 1746 I 16 Publication 1747 6 15 DU1 May 1997 0008 0009 0010 0011 SLC 5 03 and SLC 5 04 Operating Systems 11 This rung moves the decimal value for the bar code decoder Read command into the MSG instruction s Offset parameter The programming software does not allow values greater than 255 decimal to be entered into a MSG control block Offset value MOV Move L Source 1588 1588 lt Dest N7 3 0 lt The internal storage bit B3 2 gives the MSG instruction a false to true transition to send the initial command B3 2 remains latched until both DN and DA are set B3 0 MSG E Read Write Message EN 2 Type Peer to Peer DN Read Write Read ER Target Device 48
5. 5CIF Local Remote Local Control Block N7 20 Control Block Length 14 Setup Screen The initial reply from an Enhanced Bar Code Decoder will result in MSG DN 1 and MSG DA 0 This indicates that the decoder has received the command but has not yet formulated a reply The maximum time delay needed between sending the initial command and sending a poll to get the reply is 250 ms In most cases this delay could be much less 30 ms to 100 ms depending on the number of features the decoder is configured for MSG DA Bit MSG DN Bit Data Available N7 20 N7 27 TON 1 I 17E Timer On Delay EN 13 1 Timer T4 1 DN Time Base 0 01 Preset 250 lt Accum 0 lt The internal storage bit B3 2 holds the MSG instruction true until DN and DA are both set indicating completion of the command sent and reply received sequence When DN is set and DA is reset unlatching the MSG EN bit will effectively toggle the MSG instruction the same as if the MSG rung were toggled i e rung conditions made false then true The MSG instruction is toggled one time after DN and NOT DA plus some time delay to send a final poll to the decoder to get the MSG reply When the reply is received the SLC processor will set DN and DA MSG EN Bit T4 1 N7 20 E U DN 15 Publication 1747 6 15 DU1 May 1997 When the SLC processor sets both DN and DA for a MSG instruction the MSG sequence to an Enhanced Bar Code D
6. B3 0 0000 j E OSR L 0 0 1 This rung moves the decimal value for the bar code decoder trigger command into the MSG instructions Offset parameter The programming software does not allow values greater than 255 decimal to be entered into a MSG control block Offset value MOV 0001 Move Source 1588 1588 lt Dest N7 3 The internal storage bit B3 1 gives the MSG instruction a false to true 0 lt transition to send the initial command B3 1 remains latched until both the DN and DA bits are set for the MSG instruction 0002 E Read Write Message EN 1 Type Peer to Peer DN Read Write Write gR Target Device 485CIF Local Remote Local Control Block N7 0 Control Block Length 14 Setup Screen Publication 1747 6 15 DU1 May 1997 10 SLC 5 03 and SLC 5 04 Operating Systems 0003 0004 0005 0006 0007 The initial reply from an Enhanced Bar Code Decoder will result in MSG DN 1 and MSG DA 0 This simply indicates that the decoder has received the command but has not yet formulated a reply The maximum time delay needed between sending the initial command and sending a poll to get the reply is 250 ms In most cases this delay could be much less 30 ms to 100 ms depending on the number of features the decoder is configured for MSG DA Bit MSG DN Bit Data Available N7 0 N7 7 TON 1 E I F Timer On Delay EN 13 1 Timer
7. Purpose of This Document Summary of Update Affected Action to Take Pages Read the MSG Instruction Operation Document Update SLC 5 03 and SLC 5 04 Operating Systems 1747 OS302 FRN10 and 1747 0S401 FRN7 Read this document prior to using the SLC 5 03 or SLC 5 04 processors This document update contains information that updates or clarifies previously published information See the Summary of Update table below for specifics This Document Update revises the following publication Keep this Document Update for reference Publication Name Publication Number SLC 500 and MicroLogix 1000 Instruction Set 1747 6 15 Reference Manual The following table summarizes the information contained in this Document Update Change page 8 22 Using Status Bits Replace the Time Out Bit TO text with the Setting the Internal Time Out Value text 8 22 arate fies from this publication geny Disregard the ladder logic examples Refer to the Example Ladder Programs in this publication For Status W Read the Day of Week with Real or Status Word S 53 adi Time Clock sactan aithis publication Ce Hay wgek B 72 N z ite ve te R rai cation This value contains the day of week value of the clock calendar Valid range is 0 6 angen your Mearergnce Sunday 0 To disable the clock calendar write zeros to all clock and calendar words anua S 37 to S 41 Read the Int t Lat sectio
8. T4 0 DN Time Base 0 01 Preset 25 lt Accum 0 lt The internal storage bit B3 1 holds the MSG instruction true until DN and DA are both set indicating completion of the command sent and reply received sequence When DN is set and DA is reset unlatching the MSG EN bit will effectively toggle the MSG instruction the same as if the MSG rung were toggled i e rung conditions made false then true The MSG instruction is toggled one time after DN and NOT DA plus some time delay to send a final poll to the decoder to get the MSG reply When the reply is received the SLC processor will set DN and DA MSG EN Bit T4 0 N7 0 E U DN 15 When the SLC processor sets both DN and DA for a MSG instruction the MSG sequence to an Enhanced Bar Code Decoder is complete In this case the decoder has received the trigger command and has performed this command Therefore unlatch B3 1 at this time to be ready for the next request for trigger MSG DA Bit MSG DN Bit Data Available N7 0 N7 7 B3 0 U 13 1 1 If an error occurs with the MSG instruction the ER bit is set If this occurs the user can either try to resend the same message again by unlatching EN or at this point could sound an alarm or route the product down a rework loop or some other similar action If the latter choice is used you must also unlatch B3 1 at this time to be ready for the next request for trigger MSG ER Bit MSG EN
9. coder The decoder immediately replies to the SLC that it has properly received the command Y The reply sets the MSG DN bit and clears the MSG DA bit in the SLC processor The decoder then processes the command and formulates a reply to the MSG Read command with the decoded label data included in this reply and places it into its output buffer awaiting a poll The SLC processor waits a specified amount of time then re enables the same MSG Read instruction which now sends the poll to the decoder The decoder then responds to the poll command with its reply to the MSG Read command which includes the bar code label data Y The SLC processor then sets the MSG DN and MSG DA bits to signify its receipt of the data NOTE These events are described in more detail by the comments listed within the example ladder program page 9 Publication 1747 6 15 DU1 May 1997 SLC 5 03 and SLC 5 04 Operating Systems Publication 1747 6 15 DU1 May 1997 Optimizing MSG Time Out If the time delay between sending a command to an Enhanced Bar Code Decoder and polling for the reply is not long enough the MSG instruction will time out MSG TO bit 1 each time it is enabled from that point forward To re synchronize the SLC processor and the decoder you will need to cycle power on the decoder to clear its buffer There are other ways of clearing the buffers in the decoder such as
10. ction are the EN and TO bits The enable bit EN bit 15 may be unlatched but only when the done bit DN bit 13 or error bit ER bit 12 has been set indicating the successful or unsuccessful completion of the previous message In addition when a MSG is in progress and the ladder program wishes to terminate it for any reason this may be done by enabling the time out bit TO bit 8 The next time the processor scans the MSG instruction with the TO bit set it will error the MSG ER 1 The MSG instruction may then be re enabled with a false to true transition on the next program scan Initiating the MSG Instruction To invoke the MSG instruction toggle the MSG instruction rung from false to true Do not toggle the rung again until the MSG instruction has successfully or unsuccessfully completed the previous message indicated by the processor setting either the DN or ER bit Setting the Internal Time Out Value A value greater than 0 must be entered for the MSG instruction time out parameter A time out value of 0 means no time out value In other words if communication is interrupted the processor will wait forever for a reply If a reply is not received the MSG instruction will appear to be locked up When a value greater than 0 is entered for the MSG time out parameter and communication is interrupted the MSG instruction will time out after the time out expires allowing the user program to retry the same message if desi
11. d motion control devices operator interfaces sensors and a variety of software Rockwell is one of the world s leading technology companies SS i EAN Argentina Australia e Austria e Bahrain e Belgium e Brazil e Bulgaria e Canada e Chile e China PRC e Colombia Costa Rica e Croatia e Cyprus e Czech Republic e Denmark Ecuador Egypt El Salvador e Finland e France e Germany Greece Guatemala e Honduras Hong Kong e Hungary e Iceland e India e Indonesia e Ireland e Israel o Italy e Jamaica e Japan e Jordan Korea e Kuwait e Lebanon e Malaysia e Mexico e Netherlands e New Zealand e Norway e Pakistan e Peru e Philippines e Poland e Portugal e Puerto Rico e Qatar e Romania Russia ClS Saudi Arabia e Singapore Slovakia e Slovenia e South Africa Republic e Spain e Sweden Switzerland e Taiwan e Thailand e Turkey United Arab Emirates United Kingdom e United States e Uruguay Venezuela Yugoslavia Allen Bradley Headquarters 1201 South Second Street Milwaukee WI 53204 USA Tel 1 414 382 2000 Fax 1 414 382 4444 Publication 1747 6 15 DU1 May 1997 PN 40071 030 01 A 1997 Rockwell International Corporation All rights reserved Printed in USA
12. ecoder is complete In this case the decoder has received the Read command and has formulated a reply to this command Therefore unlatch B3 2 at this time to be ready for the next Read request In addition when DN and DA are both set this indicates that the data received with the read reply except no read data is valid and may be buffered or used MSG DA Bit MSG DN Bit Data Available N7 20 N7 27 B3 0 0012 1 E f U 13 1 2 COP Copy File Source N7 40 Dest N7 100 Length 10 If an error occurs with the MSG instruction the ER bit is set If this occurs the user can either try to resend the same message again by unlatching EN or at this point could sound an alarm or route the product down a rework loop or some other similar action If the latter choice is used you must also unlatch B3 2 at this time to be ready for the next Read request MSG ER Bit MSG EN Bit N7 20 N7 20 0013 E U 12 15 0014 END PLC 5 is a registered trademark of Rockwell International Corporation PLC 5 250 SLC 500 SLC 5 03 and SLC 5 04 are trademarks of Rockwell International Corporation N Rockwell Automation Allen Bradley a Rockwell Automation Business has been helping its customers improve productivity and quality for more than 90 years We design manufacture and support a broad Allen Bradley range of automation products worldwide They include logic processors power an
13. el it operates as shown below Result of Scan Bar Code Decoder Response Processor Response ea heai turns on its Good Read onboard When one of these two inputs to output wired to the SLC processor the SLC are turned on the SLC will initiate a MSG Read to the No Read turns on its No Read onboard decoder to get the label data or output wired to the SLC processor no read message data In this case the good read output will be turned on as soon as a valid read occurs and the no read output will be turned on after the decoder has attempted to read a label for a specified amount of time and could not The amount of time the decoder will attempt to read a label is variable and is called the No Read Timer For this example it is assumed that the product is moving by the scanner and if the label is not read in 2 seconds it will not be read at all Therefore the No Read Timer parameter in the bar code decoder will be set to 2 seconds Refer to the DS DD Series B Enhanced Bar Code Decoders Bulletin 2755 User s Manual publication 2755 833 for details concerning the configuration of your Allen Bradley Enhanced Bar Code Decoder SLC 5 03 and SLC 5 04 Operating Systems 7 Operating Sequence With the bar code decoder configured as previously described the following series of events will take place when a product with a good bar code label breaks the photo switch and this input to the SLC go
14. es from false to true The SLC 5 03 ladder program logic to make it happen is also included Please note that as previously stated a bar code SLC system may be configured in a variety of ways Important Sequence of Events The photo switch input to the SLC goes from false to true The SLC processors sends a trigger command to the decoder via a MSG Write command Y The decoder immediately replies to the SLC that it has properly received the command Y The reply sets the MSG DN bit and clears the MSG DA bit in the SLC processor The SLC processor then waits a specified amount of time and re enables the same MSG instruction which now sends the poll to the decoder The decoder then responds to this poll with its reply to the trigger command The SLC processor then sets the MSG DN and MSG DA bits Y The decoder then reads the bar code label and turns on the good read output wired to the SLC processor j When this good read input to the SLC goes from false to true the SLC sends a MSG Read to the decoder Messages sent by the SLC processor to the Enhanced Bar Code Decoder must be programmed as shown by the example ladder program on page 9 If this logic is not followed the communication between the two DH 485 devices could become out of sequence resulting in no data transfers between the decoder and the SLC processor To correct such a problem cycle power to the de
15. eter in a MSG instruction Therefore use an unconditioned rung with a MOV instruction to move the proper value into the Target CIF Offset field The example ladder program in this section demonstrates this Note that 1588 decimal in a MSG Write is the value which results in a properly configured Enhanced Bar Code Decoder to initiate the trigger function A value of 256 in a MSG Read requests a specified number of words of data from the bar code decoder In this example we are reading 10 words or 20 characters bytes SLC 5 03 and SLC 5 04 Operating Systems 9 Example Scanner and Decoder Configuration 2755 DS DD Series B Enhanced Bar Code Decoder Configuration Parameters Host Communications Page Scanner Configuration Parameters Scanner Control Page Discrete I O Read Package 25ms Baud Rate 19200 No Read Package 25ms Laser Light Triggered Bits Char 8 Data 1 Stop Decode Mode Host Parity Even Host Protocol DH485 PCCC 1 Device Address 2 No Read Time 2000 ms Inter Scan Time none Capture Count 2 ACK Char none Symbols Scan 1 NAK Char none Symbols Package 1 Large Buffer No Match Complete 1 Send Host Message Immediately after Valid Package Transmission Check none Example Ladder Program This rung detects the Photo Switch input going from false to true and latches internal storage bit B3 1 Photo Switch Initiate Write MSG I 1 B3 0
16. n i is ental rea ee ni Change the Entry Time values for SLC 5 03 and SLC 5 04 processors to the new values D 7 BEB Manual gy listed in this publication Read the Interfacing with Enhanced H 28 Bar Code Decoders section in this Add the Interfacing with Enhanced Bar Code Decoders section of this publication to publication Note Change in your Reference Manual Appendix H Application Example Programs Publication 1747 6 15 DU1 May 1997 2 SLC 5 03 and SLC 5 04 Operating Systems MSG Instruction Operation for SLC 5 03 Processors 1747 0S302 FRN9 or later and SLC 5 04 Processors 1747 0S401 FRN5 or later Publication 1747 6 15 DU1 May 1997 The following recommendations for the use of the MSG message instruction apply to SLC 5 03 processors 1747 OS302 FRN9 or later and SLC 5 04 processors 1747 OS401 FRN5 or later The recommendations must be followed for proper operation of the MSG instruction Two example ladder programs are included to illustrate programming the MSG instruction Recommendations for Using the MSG Instruction Limitations for Manipulating the Control Block Bits Do not manipulate the MSG instruction control block values For example do not clear the first word of the control block do not unlatch the time out control bit and so on The only MSG instruction control bits that may be manipulated by the ladder program without adversely affecting the operation of the instru
17. red 0000 0001 0002 0000 0001 0002 0003 SLC 5 03 and SLC 5 04 Operating Systems 3 Example Ladder Programs Enabling the MSG Instruction Via Ladder Logic The MSG instruction will be enabled during the initial processor program scan and each time the MSG completes i e when the DN or ER bit is set MSG Read Write Message EN Type Peer to Peer DN Read Write Read __ ER Target Device 500CPU Local Remote Local Control Block N7 0 Control Block Length 14 Setup Screen MSG Done Bit MSG Enable Bit N7 0 N7 0 E U 13 15 MSG Error Bit N7 0 E 12 END Enabling the MSG Instruction Via User Supplied Input As long as input 1 1 0 is set or anytime it becomes set the MSG instruction in the next rung will be enabled This program is an example of controlling when the MSG instruction operates Input I 1 0 could be any user supplied bit used to control when MSGs are sent MSG Enable Bit N7 0 B3 0 b H me 1 f L 0 15 0 The MSG instruction will be enabled with each false to true transition of bit B3 0 0 B3 0 MSG J E Read Write Message EN 0 Type Peer to Peer DN Read Write Read _ ER Target Device 500CPU Local Remote Local Control Block N7 0 Control Block Length 14 Setup Screen MSG Done Bit N7 0 B3 0 E U 13 0 MSG Error Bit N7 0
18. sending a Clear Buffers command or a Reset command to the decoder However the best way to handle this issue is to never let it happen Optimizing the time delay between sending the initial command and polling for the reply is the best way to accomplish this The delay must be long enough so the decoder will have enough time to formulate a reply to the command and short enough to not impact the throughput of the application Example MSG Instruction Configuration The example SLC 5 03 and SLC 5 04 ladder program demonstrates how to send commands to an Enhanced Bar Code Decoder and then after a time delay poll for a reply The internal setup screen parameters for the two MSG instructions in the example ladder program are shown below along with the necessary Enhanced Bar Code Decoder configuration parameters SLC 5 03 and SLC 5 04 Internal Set Up Screen Parameters MSG 1 MSG 2 Type peer to peer peer to peer Read write write read Target device 485CIF 485CIF Local remote local local Control block N7 0 N7 20 Channel 1 1 Target Node 2 2 Our source file address N7 15 N7 40 Target CIF offset 0 0 Message length in elements 1 10 Message time out seconds 5 5 The Target CIF Offset when working with Enhanced Bar Code Decoders as slaves on DH 485 must contain a value greater than 255 However 255 is the largest value SLC programming software will allow you to enter into this param
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1747 6.15 DU1