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EZT-570S User Communication Reference Manual

 

   

 

15 

Exception Responses 

When the EZT-570S cannot process a command, it returns an exception response and sets the high 
bit (0x80) of the command. 
 
0x01 illegal 

command 

0x02 

illegal data address 

0x03 

illegal data value 

 
 

Packet returned from the EZT-570S:   

 
controller address (1 byte) 
c 0x80 
exception code (0x01 or 0x02 or 0x03) 
CRC low byte 
CRC high byte 

 

2.3.2 Error 

Checking 

In Modbus communications, every message sent from the master (your software) receives a 
response from the slave (EZT-570S), including write commands.  Thus, after each command sent, 
you must read the controller response before sending the next message.  This provides the method 
of error checking in order to verify that the message you sent was received correctly, and that the 
controller is operating accordingly.  This allows you to then determine the appropriate recovery 
response in case the message was not received correctly by the controller, and what action is to be 
taken by an operator and/or the software itself. 
 
The exception responses provide a basic form of error checking.  When an exception response is 
received, the code provided in the response will tell you what the error was in the sent message.  
However, this is only valid if the controller receives the message you sent, and there was an out-of-
range value or simple transmission error in the message.  It does not validate incomplete or failed 
transmissions.  To insure that the data you receive from a read command is correct, and that the 
controller properly received a write command, you must parse the controller’s response and validate 
the return message to insure it is correct. 
 
In order to validate that the message you received is correct, you must calculate the CRC for the 
received message and compare it with the CRC that the controller appended to the message.  This 
verifies that the data you received was what the EZT-570S sent.  If the CRC’s do not match, there 
was an error in the transmission and the entire message should be ignored.  This could then be 
followed by an attempt to resend the failed command, or halt operation and alert an operator. 
 

Example:

   Read registers 60 and 61 (loop 1 set point and process variable) of the EZT-570S at 

address 1. 

 
Command sent to the EZT-570S : 

 

 

01 03 00 3C 00 02 04 07 

Message received from the EZT-570S:   

01 03 04 03 0D 01 F3

 

2A 61 

 
 

Calculated CRC: 

2A61 

(calculated from message 01 03 04 03 0D 01 F3) 

Received CRC:  

2A61 

 

The calculated CRC matches the received CRC, the message is valid.  Note that the last two 
bytes of the received message are not used to calculate the CRC.  The last two bytes are the 
CRC that the EZT-570S appended to the message.  Do not include them when calculating 
the CRC.

 

nn nn nn  nn 

nn 

Содержание EZT-570S

Страница 1: ...EZT570S User Communication Reference Manual RevC docC 450 V1 2 730 V1 0 EZT 570S User Communication Reference Manual ...

Страница 2: ...ol 8 2 3 Write your own Modbus Application 10 2 3 1 Packet Syntax 12 2 3 2 Error Checking 15 2 3 3 Transmitting and Receiving Messages 16 2 4 EZT 570S Control Registers 18 2 5 EZT 570S Automatic Ramp Soak Program Registers 35 2 5 1 Progran Download Algorithm 39 2 5 2 Sending a Ramp Soak Program to the EZT 570S 41 2 5 3 Starting a Ramp Soak Program in the EZT 570S 42 Appendix Terms and Definitions ...

Страница 3: ...ard Code for Information Interchange called ASCII Bits and Bytes The word bit is simply the contraction of the words binary digit A bit is the basic unit in ASCII It is either a 1 or a 0 A byte is a string of eight bits that a computer treats as a single character ASCII can use a single byte to represent each letter of the alphabet each digit and each punctuation mark we use ASCII The ASCII code d...

Страница 4: ...M Ctrl Y 25 00011001 19 Y Shift Y 89 01011001 59 SUB Ctrl Z 26 00011010 1A Z Shift Z 90 01011010 5A ESC Ctrl 27 00011011 1B 91 01011011 5B FS Ctrl 28 00011100 1C 92 01011100 5C GS Ctrl 29 00011101 1D 93 01011101 5D RS Ctrl 30 00011110 1E Shift 6 94 01011110 5E US Ctrl _ 31 00011111 1F _ Shift 95 01011111 5F SP SPACE 32 00100000 20 96 01100000 60 Shift 1 33 00100001 21 a A 97 01100001 61 Shift 34 0...

Страница 5: ... a clearing of the throat to get someone s attention start bit and a pause at the end of a phrase stop bit Both help the listener understand the message A stop bit has a value of 1 or a mark state and it can be detected correctly even if the previous data bit also had a value of 1 This is accomplished by the stop bit s duration Stop bits can be 1 1 5 or 2 bit periods in length CSZ has chosen to us...

Страница 6: ...ti drop system more than one EZT 570S on the link The following list references some vendors who sell these converters Should your PC have the appropriate interface just connect using the wiring shown in the Getting Started section For EIA 485 the terminal marked A usually connects to the T R while the B terminal connects to the T R of the EZT 570S controller The standards do not specify the wire ...

Страница 7: ...ontroller correctly with out properly setting this Your converter may also require settings through dip switches to set up communications parameters like baud rate data bits start bits stop bits and handshaking The converter may also require a separate power supply Some converters get their power from the handshake lines of the PC If you rely on this method you will need to wire these additional l...

Страница 8: ... this protocol for process control systems called Modbus It has the advantage over other protocols of being extremely reliable in exchanging information This protocol works on the principle of packet exchanges The packet contains the address of the controller to receive the information a command field that says what is to be done with the information and several fields of data Reading from these r...

Страница 9: ...r Start at the beginning of the packet char_ptr start_of_packet Initialize CRC crc 0xFFFF Loop through the entire packet do Exclusive OR the byte with the CRC crc unsigned int char_ptr Loop through all 8 data bits bit_count 0 do If the LSB is 1 shift the CRC and XOR the polynomial mask with the CRC if crc 0x0001 crc 1 crc 0xA001 If the LSB is 0 shift the CRC only else crc 1 while bit_count 7 while...

Страница 10: ... compatibility of any software package with your Contact the software manufacturer for more information on applying their software LabView by National Instruments 6504 Bridge Point Parkway Austin TX 78730 5039 Phone 512 794 0100 http www natinst com OI 2000 by Software Horizons Inc 10 Tower Office Park Suite 200 Woburn MA 01801 2120 Phone 617 933 3747 http www shorizons com SpecView by SpecView LL...

Страница 11: ...value of 424 in order for the EZT 570S to be set correctly Likewise a process value read from the EZT 570S with a value of 967 is actually 96 7 degrees Consult the parameter table for the proper format of each value 5 When monitoring a process try to keep the number of read and write commands to a minimum of 500ms between exchanges to a single controller Continuously reading data at a faster rate ...

Страница 12: ...nd 0x03 This command returns from 1 to 60 registers This command is to be used for reading one or more data locations from the EZT 570S Packet sent to EZT 570S controller address 1 byte read command 0x03 starting register high byte starting register low byte number of registers high byte 0x00 number of registers low byte CRC low byte CRC high byte Packet returned from EZT 570S controller address 1...

Страница 13: ...mmand is to be used for setting control values in the EZT 570S To set multiple values repeat the command for each data location Packet sent to EZT 570S controller address 1 byte write command 0x06 register high byte register low byte data high byte data low byte CRC low byte CRC high byte Packet returned from EZT 570S controller address 1 byte write command 0x06 register high byte register low byt...

Страница 14: ...ill not be executed Packet sent to EZT 570S controller address 1 byte write command 0x10 starting register high byte starting register low byte number of registers to write high byte 0x00 number of registers to write low byte 0x0F number of data bytes 0x1E data high byte data low byte register n data high byte register n data low byte CRC low byte CRC high byte Packet returned from EZT 570S contro...

Страница 15: ...troller receives the message you sent and there was an out of range value or simple transmission error in the message It does not validate incomplete or failed transmissions To insure that the data you receive from a read command is correct and that the controller properly received a write command you must parse the controller s response and validate the return message to insure it is correct In o...

Страница 16: ...message generate the CRC and append it to the message body Once the message is completely assembled it can then be sent out the serial port as a completed packet This will insure that the message reaches the EZT 570S within the proper framing Receiving Messages Due to the fact that Modbus RTU protocol does not have start of transmission or end of transmission characters if the serial port driver y...

Страница 17: ... of data bytes in message YES Write Command 0x06 10 NO Exception Response 0x8_ YES YES Read remaining 8 bytes from serial port to obtain complete message Read remaining 3 bytes from serial port to obtain complete message Read in number of data bytes from message plus 2 additional CRC bytes Calculate the CRC for the message and compare to CRC received NO YES CRC s match Disregard message transmissi...

Страница 18: ...MODELS DTS MODELS LOOP 1 TEMPERATURE TEMPERATURE TEMPERATURE TEMPERATURE HOT CHAMBER BATH LEFT CHAMBER 2 PRODUCT HUMIDITY ALTITUDE HUMIDITY COLD CHAMBER BATH CENTER CHAMBER 3 PRODUCT PRODUCT ALTITUDE PRODUCT RIGHT CHAMBER 4 PRODUCT DUT LEFT BASKET 5 DUT RIGHT BASKET The chamber events also vary based on the model of chamber and options present In order to turn the chamber and associated options on...

Страница 19: ...ch bit of the word indicates an on off status for a specific setting or condition In handling these values it is recommended that the word be converted to its binary equivalent By converting the value to its binary equivalent it produces a Boolean array of true bit on 1 and false bit off 0 values This allows each bit to be examined individually In the same manner creating a Boolean array of 16 bit...

Страница 20: ...32767 minutes 10 0x000A Defrost Status R B7 B7 11 0x000B Time Remaining Until Next Defrost R 0 32767 minutes 12 0x000C Product Control R B8 B8 13 0x000D Product Control Upper Set Point R W 3276 8 3276 7 C1 14 0x000E Product Control Lower Set Point R W 3276 8 3276 7 C1 15 0x000F Condensation Control Off On R W 0 1 16 0x0010 Condensation Control Monitor Mode R W B9 B9 17 0x0011 Condensation Control ...

Страница 21: ...3276 8 3276 7 C1 48 0x0030 Program Loop 3 Target Set Point R 3276 8 3276 7 C1 49 0x0031 Program Loop 4 Target Set Point R 3276 8 3276 7 C1 50 0x0032 Program Loop 5 Target Set Point R 3276 8 3276 7 C1 51 0x0033 Last Jump Made from Step R 1 99 52 0x0034 Last Jump Made to Step R 1 99 53 0x0035 Total Jumps Made R 0 32767 54 0x0036 Alarm Reset W B18 B18 55 0x0037 Input Alarm Status R B19 B19 56 0x0038 ...

Страница 22: ...1 86 0x0056 Loop 3 Percentage of Output Out R 100 00 100 00 C1 87 0x0057 Loop 3 Autotune Status R W B24 B24 88 0x0058 Loop 3 Upper Set Point Limit R W 3276 8 3276 7 C1 89 0x0059 Loop 3 Lower Set Point Limit R W 3276 8 3276 7 C1 90 0x005A Loop 3 Alarm Type R W B25 B25 91 0x005B Loop 3 Alarm Modes R W B26 B26 92 0x005C Loop 3 Alarm Output Selection R W B27 B27 93 0x005D Loop 3 High Alarm Set Point R...

Страница 23: ...igh Alarm Set Point R W 3276 8 3276 7 C1 125 0x007D Monitor 1 Low Alarm Set Point R W 3276 8 3276 7 C1 126 0x007E Monitor 1 Alarm Differential R W 0 0 3276 7 C1 127 0x007F Monitor 2 Process value PV R 3276 8 3276 7 C1 128 0x0080 Monitor 2 Alarm Type R W B25 B25 129 0x0081 Monitor 2 Alarm Modes R W B26 B26 130 0x0082 Monitor 2 Alarm Output Selection R W B27 B27 131 0x0083 Monitor 2 High Alarm Set P...

Страница 24: ...Set Point R W 3276 8 3276 7 C1 160 0x00A0 Monitor 6 Low Alarm Set Point R W 3276 8 3276 7 C1 161 0x00A1 Monitor 6 Alarm Differential R W 0 0 3276 7 C1 162 0x00A2 Monitor 7 Process value PV R 3276 8 3276 7 C1 163 0x00A3 Monitor 7 Alarm Type R W B25 B25 164 0x00A4 Monitor 7 Alarm Modes R W B26 B26 165 0x00A5 Monitor 7 Alarm Output Selection R W B27 B27 166 0x00A6 Monitor 7 High Alarm Set Point R W 3...

Страница 25: ...related to the other bits in the parameter B1 B2 Parameter Value Range Low Range High Description High Byte 0 99 Year Low Byte 1 12 Month B3 Parameter Value Range Low Range High Description High Byte 1 31 Day Low Byte 0 6 Day of Week B4 Parameter Value Range Low Range High Description High Byte 0 23 Hour Low Byte 0 59 Minutes Example Read of registers 1 to 4 for the current time from the EZT 570S ...

Страница 26: ...6 Parameter Value Description 0 Disabled 1 Manual 2 Auto B7 Parameter Value Description 0 Inactive 1 In Defrost 2 In Prechill B8 B9 Parameter Value Description 0 Off 1 Deviation 2 Process 5 Deviation with Event Enable Disable 6 Process with Event Enable Disable Parameter Value Description 1 Single 2 Lowest 4 Highest 8 Average ...

Страница 27: ...bit number defines the position index of the bit element in the word which can be thought of as an array of bits starting at the LSB The bit values then become 00000000 11100011 The decimal equivalent of the binary array is 227 0x00E3 By setting register 17 to a value off 227 the selected inputs will be used B11 Parameter Value Range Low Range High Degrees C 0 10 0 Degrees F 0 18 0 Setting the ind...

Страница 28: ... the bit at position index zero of the word should be set The bit values of the word then become 00000000 00000001 The decimal equivalent of the binary array is 1 0x0001 By setting register 22 to a value of 1 the chamber will turn on Example Turn on customer events 7 10 14 and 15 By comparing the event numbers to their bit positions set the bits in the word accordingly 0110001001000000 The decimal...

Страница 29: ... r o e e T t s Assemble the ASCII characters in order from low to high byte starting with register 26 in order to assemble the Program name Store Test Note that null characters are not used in the Program name A space 0x20 will be used is used in place of a null character to maintain the 10 character name length if the Program name is not ten characters long B16 Parameter Value Range Low Range Hig...

Страница 30: ...nput 2 4 Input 3 8 Input 4 16 Input 5 32 Input 6 64 Input 7 128 Input 8 256 Input 9 512 Input 10 1024 Input 11 2048 Input 12 4096 Input 13 8192 Digital Input B18 Parameter Value Description 1 Alarm Reset Silence 2 Pumpdown Reset Once the set function is executed this parameter automatically resets to zero 0 ...

Страница 31: ...Communications Failure Bit15 Not Assigned B20 Parameter Value Description Bit0 Input 1 Alarm Bit1 Input 2 Alarm Bit2 Input 3 Alarm Bit3 Input 4 Alarm Bit4 Input 5 Alarm Bit5 Input 6 Alarm Bit6 Input 7 Alarm Bit7 Input 8 Alarm Bit8 Input 9 Alarm Bit9 Input 10 Alarm Bit10 Input 11 Alarm Bit11 Input 12 Alarm Bit12 Input 13 Alarm Bit13 15 Not Assigned The individual bits of the word indicate specific ...

Страница 32: ...it10 System 2 B Discharge Temperature Bit11 System 2 B Protection Module Bit12 Not Assigned Bit13 System B Floodback Monitor Bit14 15 Not Assigned y The individual bits of the word indicate specific alarm conditions When the bit is on 1 the alarm is present More than one alarm can be present at a time The A and B plenum designations are for chambers that are equipped with two conditioning plenums ...

Страница 33: ... Start Autotune 2 Autotune in Progress 4 Cancel Autotune B25 Parameter Value Description 0 Alarm Off 1 Absolute High 5 Absolute Low 7 Absolute Both 24 Deviation High 40 Deviation Low 56 Deviation Both The individual bits of the word indicate specific alarm conditions When the bit is on 1 the alarm is present More than one alarm can be present at a time The alarms are in sequential order as they ap...

Страница 34: ...28 Parameter Value Description 0 Online 1 Offline Downloading Program C1 The units of measure and range of a loop or monitor input is dependant upon the configuration of the input and or the units of temperature selection Celsius or Fahrenheit of the EZT 570S The decimal point position for the loop or monitor input is an implied value Thus a register value of 345 will represent an actual process v...

Страница 35: ...include autostart settings the program name the length of the program number of steps and guaranteed soak band settings These values are always transmitted as the first step of the program Register Address Parameter Description Data D Range E F Type Low High Unit 200 0x00C8 Autostart On Off W E1 E1 201 0x00C9 Year Month for Autostart W E2 E2 202 0x00CA Day DOW for Autotstart W E3 E3 203 0x00CB Tim...

Страница 36: ...Loop 4 Set Point W 3276 8 3276 7 PV 229 0x00E5 Loop 5 Set Point W 3276 8 3276 7 PV All remaining steps of the Program follow the same format and data structure as is represented for step one above Up to the following 1470 registers are used to contain the additional step data of the Program as required for steps 2 through 99 Since few if any programs will contain the maximum of 99 steps it is only...

Страница 37: ...f this parameter E4 See B4 in Section 2 4 for information on the range of this parameter E5 These parameters contain data which represent up to ten ASCII characters in order to display the name of the currently loaded or operating program in the EZT 570S See B15 in Section 2 4 for information on the range of these parameters E6 Parameter Value Range Low Range High Description High Byte 0 59 Minute...

Страница 38: ...lue Description 0 Wait for Disabled no loop selected 1 Wait For Loop 1 2 Wait For Loop 2 4 Wait For Loop 3 8 Wait For Loop 4 16 Wait For Loop 5 E10 Parameter Value Description 0 Wait for Disabled no input selected 1 Wait For Monitor 1 2 Wait For Monitor 2 4 Wait For Monitor 3 8 Wait For Monitor 4 16 Wait For Monitor 5 32 Wait For Monitor 6 64 Wait For Monitor 7 128 Wait For Monitor 8 If an event i...

Страница 39: ...o here Check to see if profile is running before downloading profile see EZT register list for profile status register if EZT is offline mode or downloading a profile do not start profile download from PC and alert user If G_vAry f_EztNum 180 1 Then MsgBox Local EZT 570S is in the offline mode or running downloading a profile vbCrLf _ Writes from the PC can not be initiated at this time _ vbInform...

Страница 40: ...te 10 End Select Else elements 1 to 99 of profarray which holds data for each segment Select Case x Case 0 To 6 hours mins secs chamber events cust events gs events wait or loop input wait for monitor input first 6 elements require no scale by 10 writeValue CInt profileData x f_profRegsToWrite Case 7 wait for input setpoint value for SP so scale by 10 writeValue CInt profileData x f_profRegsToWrit...

Страница 41: ...ve been received the EZT downloads the program into the control module memory During this transfer register 180 will be set to 1 to indicate that the process is taking place Once the register value returns to zero the program is ready to be started If an error occurs during the transfer process from the PC to the EZT the program transfer process should be stopped at the PC The data sent to the EZT...

Страница 42: ... minimum 1 second pause between write commands Send program data 200 thru 214 1 second pause Send step 1 data 215 thru 229 1 second pause Send step 2 data 230 thru 244 1 second pause Send last step data Is EZT online 180 0 NO Set start step 37 1 99 YES Set program to run 24 4 Done 1 second pause EZT begins program download NO Write error during download YES 20 second pause EZT clears program buffe...

Страница 43: ...EZT 570S User Communication Reference Manual A 1 A Appendix ...

Страница 44: ...rter This device will convert from one hardware interface to another such as from EIA 232 to EIA 485 The converter may be transparent to the software which means you do not have to give any special considerations to software programming CRC When data is corrupted during transmission a method is used to return the data to its correct value This can be accomplished through several methods parity che...

Страница 45: ...A An association in the US that establishes standards for electronics and data communications Encode To embed information into a piece of data This is the reverse of decode Example let 01000001 stand for an A Error Correction When an inconsistency is in the data a method is used to detect and or return the data to its correct value This can be done through several methods parity checksum and CRC c...

Страница 46: ...nes the devices are networked Node A point of interconnection to a network Noise Immunity The ability of communication lines to ignore electrical noise generated in the lines by nearby magnetic and electrostatic fields Odd This term is used with parity See parity Parallel Communication using this method transfers eight bits or one byte at a time over eight data wires and one ground wire This metho...

Страница 47: ...nsmission of a data bit logic 0 see logic level Usually this is the most positive voltage value in serial communications Start Bit A binary bit or logic level that represents when the serial data information is about to start at the beginning of a character or byte This voltage level is positive Stop Bit A binary bit or logic level that represents when the serial data information is complete at th...

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