Red Lion PAXCD Serial Communications Plug
Contents
1. Data is transmitted one byte at a time with a variable idle period between characters 0 to Each ASCH character is framed with a beginning start bit an optional error detection parity bit and one or more ending stop bits The data format and baud rate must match that of other equipment in order for communication to take place The figures list the data formats employed by the meter Start bit and Data bits Data transmission always begins with the start bit The start bit signals the receiving device to prepare for reception of data One bit period later the least significant bit of the ASCII encoded character is transmitted followed by the remaining data bits The receiving device then reads each bit position as they are transmitted Since the sending and receiving devices operate at the same transmission speed baud rate the data is read without timing errors Start bit q DLE O bo b1 b2 b3 b4 bs bs O J11 IDLE 8 data no parity 1 stop DLE O bo b1 b2 b3 b4 bs bs P 11 IDLE 7 data parity stop DLE O bo b1 b2 b3 b4 bs be 1 IDLE 7 data no parity 2 stop Note bp bs is ASCII data Character Frame Figure Parity bit After the data bits the parity bit is sent The transmitter sets the parity bit to a zero or a one so that the total number of ones contained in the transmission including the parity bit is either even or od2. one byte for sign one byte for decimal point 13 lt CR gt carriage return 14 lt LF gt line feed 15 lt SP gt Space 16 lt CR gt carriage return 17 lt LF gt line feed 1 12 These characters only appear in the last line of a block print The abbreviated response suppresses the node address and register ID leaving only the numeric part of the response Meter Response Examples 1 Node address 17 full field response Input 875 17 INP 875 lt CR gt lt LF gt 2 Node address 0 full field response Setpoint 2 250 5 SP2 250 5 lt CR gt lt LF gt 3 Node address 0 abbreviated response Setpoint 2 250 last line of block print 250 lt CR gt lt LF gt lt SP gt lt CR gt lt LF gt SERIAL COMMANDS FOR PAX SOFTWARE CSR Control Status Register The Control Status Register is used to both directly control the meter s outputs setpoints and analog output and interrogate the state of the setpoint outputs The register is bit mapped with each bit position within the register assigned to a particular control function The control function are invoked by writing to each bit position The bit position definitions are bit 0 Setpoint 1 Output Status 0 output off 1 output on bit 1 Setpoint 2 Output Status 0 output off 1 output on bit 2 Setpoint 3 Output Status 0 output off 1 output on bit 3 Setpoint 4 Output Status 0 output off 1 output on bit 4 Manual Mode 0 automatic mo
3. PIN 5 COMMON FEMALE Extended Comms Connection Figure RS232 is intended to allow only two devices to communicate over distances up to 50 feet Data Terminal Equipment DTE transmits data on the Transmitted Data TXD line and receives data on the Received Data RXD line Data Computer Equipment DCE receives data on the TXD line and transmits data on the RXD line The PAX emulates a DTE If the other device connected to the meter also emulates a DTE the TXD and RXD lines must be interchanged for communications to take place This is known as a null modem connection Most printers emulate a DCE device while most computers emulate a DTE device Some devices cannot accept more than two or three characters in succession without a pause in between In these cases the meter employs a busy function As the meter begins to transmit data the RXD line RS232 is monitored to determine if the receiving device is busy The receiving device asserts that it is busy by setting the RXD line into a space condition logic 0 The meter then suspends transmission until the RXD line is released by the receiving device RS485 Communications The RS485 communication standard allows the connection of up to 32 devices on a single pair of wires distances up to 4 000 ft and data rates as high as 10M baud the PAX is limited to 19 2k baud The same pair of wires is used to both transmit and receive data An RS485 bus is therefore always ha
4. 000 0 000 card the actual output signal may 0 005 0 0025 differ 0 15 FS from the table 3047 values The output signal corresponds to the range selected 4094 20 mA or 10 V 4095 Writing to this register while the meter is in the manual mode causes the output signal to update immediately While in the automatic mode this register may be written to but the output will not update until the meter is placed in manual mode Examples 1 Set output to full scale V14095 2 Set output to zero scale VIO At the start of the time interval t the computer program prints or writes the string to the com port thus initiating a transmission During t the command characters are under transmission and at the end of this period the command terminating character is received by the meter The time duration of t is dependent on the number of characters and baud rate of the channel t 10 of characters baud rate At the start of time interval t the meter starts the interpretation of the command and when complete performs the command function This time interval t varies from 2 msec to 50 msec If no response from the meter is expected the meter is ready to accept another command If the meter is to reply with data the time interval t is controlled by the use of the command terminating character The standard command line terminating character is This terminating character results in a response time
5. 2 byte Node Address field 00 99 3 lt SP gt Space 4 6 3 byte Register Mnemonic field 12 byte data field 10 bytes for number one byte for sign one byte for decimal point The T command may be a different byte length 19 lt CR gt carriage return 20 lt LF gt line feed 21 lt SP gt Space 22 lt CR gt carriage return 23 lt LF gt line feed These characters only appear in the last line of a block print 7 18 The first two characters transmitted are the node address unless the node address assigned 0 in which case spaces are substituted A space follows the node address field The next three characters are the register ID Serial Mnemonic The numeric data is transmitted next The numeric field is 12 characters long to accommodate the 10 digit totalizer with the decimal point position floating within the data field Negative value have a leading minus sign The data field is right justified with leading spaces Register Identification Chart Register Value Description ID Applicable Commands Comments Input INP T P Reset command resets total to Total TOT zero T P R Reset command resets MAX to Max Input MAX current reading T P R Reset command resets MIN to Min Input MIN current reading T P R Reset command resets the Setpoint 1 SP1 setpoint output T P V R Reset command resets the THEE setpoint output Setpoint 2 SP2 Reset command r
6. ES Enters the sub menu to select those meter parameters to appear in the block print For each parameter in the sub menu select Y 5 for the parameter to appear with the block print and AB to disable the parameter Setpoints 1 4 are setpoint plug in card dependent Input Value up YES no Max and Min Values hiLG YES no Total Value tok YES no Setpoint values SPRE YES no Sending Commands and Data When sending commands to the meter a string containing at least one command character must be constructed A command string consists of a command character a value identifier numerical data if writing data to the meter followed by a the command terminator character or Command Chart Command Description Address a specific meter Must be followed by one or two digit node address Not required when node address 0 Read a register from the meter Must be followed by register ID character Write to register of the meter Must be Value change write followed by register ID character and numeric data Reset a register or output Must be followed by register ID character Block Print Request Initiates a block print output Registers are read defined in programming Node Address Specifier Transmit Value read Reset Command Siring Construction The command string must be constructed in a specific sequence The meter does not respond with an error message to illegal comman
7. and Meter String Response Transmission Time Ready pe t aoa Tas t2 RESPONSE FROM M Ready m ti t ts Ready Command First Reply Terminator Character Transmission Received of Reply Time ER Timing Diagram Figure Examples 1 Set manual mode turn all setpoints off 76 5 4 3 2 1 Orbit location VJ lt 30 gt or VJO ASCIIO 00 1 1 0 0 0 0 or lt 30 gt V is command write J is CSR and is terminator 2 Turn SP1 SP3 outputs on and SP2 SP4 outputs off 76 5 4 3 2 1 Orbit location VJ lt 35 gt or VJ5 ASCII5 0 0 1 1 01 0 1 or lt 35 gt 3 Select Automatic mode 76 5 4 3 2 1 Or bit location VJ lt 40 gt or VJ ASCIL 0 1 0 0 0 0 0 O or lt 40 gt Note Avoid writing values lt OA gt LF lt OD gt CR lt 24 gt and lt 2E gt to the CSR These values are interpreted by the meter as end of command control codes and will prematurely end the write operation AOR Analog Output Register The Analog Output Register controls the analog output of the meter The manual mode must first be engaged by setting bit 4 of the Control Status Register The range of values of this register is 0 to 4095 which corresponds to 0 mA 0 V and 20 mA 10 V respectively The table lists correspondence of the output signal with the register value y Output Signal Register Value I mA V V Due to the absolute accuracy rating and resolution of the output 0 0
8. d This bit is used by the receiver to detect errors that may occur to an odd number of bits in the transmission However a single parity bit cannot detect errors that may occur to an even number of bits Given this limitation the parity bit is often ignored by the receiving device The PAX meter ignores the parity bit of incoming data and sets the parity bit to odd even or none mark parity for outgoing data Stop bit The last character transmitted is the stop bit The stop bit provides a single bit period pause to allow the receiver to prepare to re synchronize to the start of a new transmission start bit of next byte The receiver then continuously looks for the occurrence of the start bit This page intentionally left blank 7 Red Lion Controls 20 Willow Springs Circle York PA 17402 Tel 1 717 767 6511 Fax 1 717 764 0839 LIMITED WARRANTY The Company warrants the products it manufactures against defects in materials and workmanship for a period limited to one year from the date of shipment provided the products have been stored handled installed and used under proper conditions The Company s liability under this limited warranty shall extend only to the repair or replacement of a defective product at The Company s option The Company disclaims all liability for any affirmation promise or representation with respect to the products The customer agrees to hold Red Lion Controls harmless from defend and i
9. de 1 manual mode bit 5 Always stays 0 even if 1 is sent bit 6 Sensor Status PAXT only 0 sensor normal 1 sensor fail bit 7 Always stays 0 even if 1 is sent Although the register is bit mapped starting with bit 7 HEX lt gt characters are sent in the command string Bits 7 and 5 always stay a zero even if a 1 is sent This allows ASCII characters to be used with terminals that may not have extended character capabilities Writing a 1 to bit 4 of CSR selects manual mode In this mode the setpoint outputs are defined by the values written to the bits b0 b1 b2 b3 and the analog output is defined by the value written to the AOR Internal control of these outputs is then overridden In automatic mode the setpoint outputs can only be reset off Writing to the setpoint output bits of the CSR has the same effect as a Reset command R The contents of the CSR may be read to interrogate the state of the setpoint outputs and to check the status of the temperature sensor PAXT only Command Response Time The meter can only receive data or transmit data at any one time half duplex operation The meter ignores commands while transmitting data but instead uses RXD as a busy signal When sending commands and data to the meter a delay must be imposed before sending another command This allows enough time for the meter to process the command and prepare for the next command NO REPLY FROM METER Comm
10. ds The following procedure details construction of a command string 1 The first 2 or 3 characters consist of the Node Address Specifier N followed by a 1 or 2 character node address number The node address number of the meter is programmable If the node address is 0 this command and the node address itself may be omitted This is the only command that may be used in conjunction with other commands 2 After the optional address specifier the next character is the command character 3 The next character is the register ID This identifies the register that the command affects The P command does not require a register ID character It prints according to the selections made in print options 4 If constructing a value change command writing data the numeric data is sent next 5 All command strings must be terminated with the string termination characters or The meter does not begin processing the command string until this character is received See timing diagram figure for differences of and terminating characters Receiving Data Data is transmitted by the meter in response to either a transmit command T a print block command P or User Function print request The response from the meter is either a full field transmission or an abbreviated transmission In this case the response contains only the numeric field The meter response mode is established in programming Full Field Transmission Byte Description 1 2
11. esets the Setpoint 3 SP3 setpoint output T P V R Reset command resets the Setpoint 4 SP4 setpoint output T P V R Analog Output Register ROR TV Control Status Register CSR i Applies to manual mode Command String Examples 1 Node address 17 Write 350 to Setpoint 1 response delay of 2 msec min String NI7VE350 2 Node address 5 Read Input value response delay of 50 msec min String NSTA 3 Node address 0 Reset Setpoint 4 output response delay of 50 msec min String RH Sending Numeric Data Numeric data sent to the meter must be limited to 5 digits 19 999 to 99 999 If more than 5 digits are sent the meter accepts the last 5 Leading zeros are ignored Negative numbers must have a minus sign The meter ignores any decimal point and conforms the number to the scaled resolution For example the meter s scaled decimal point position 0 0 and 25 is written to a register The value of the register is now 2 5 In this case write a value 25 0 Note Since the meter does not issue a reply to value change commands follow with a transmit value command for readback verification The end of the response string is terminated with a carriage return lt CR gt and lt LF gt When block print is finished an extra lt SP gt lt CR gt lt LF gt is used to provide separation between the blocks Abbreviated Transmission Byte Description 12 byte data field 10 bytes for number
12. lf duplex that is data cannot be received and transmitted simultaneously PAX METER RECEIVING DEVICE 5V 33K Transmit Enable pe or ppe or i4 COMM 1 r i5 Nc OPTIONAL Terminal Block Connection Figure gel TU v o o N n on 3 3 3 pe p os o O 10 0 ZO EO E A 21 345 PAX CONNECTOR Extended Comms Connection Figure MODULE 7 SERIAL COMMUNICATIONS PARAMETERS 7 5ri PARAMETER MENU Meter Abbreviated Address Printing It is necessary to match the PAX meter s serial communications parameters to the host s parameters before communications can be established This is accomplished by using the PAX front panel keys to enter 7 5rt Indicates Program Mode Alternating Display bAUd c S 9600 9600 Selection Value Factory Settings are shown Parameter BAUD RATE bRud 300 i200 800 19200 EDD 2400 9600 S 9680 Set the baud rate to match that of other serial communications equipment Normally the baud rate is set to the highest value that all of the serial communications equipment is capable of transmitting DATA BIT dREAlS 1 g S 7 Select either 7 or 8 bit data word lengths Set the word length to match that of other serial communication equipment Since the meter receives and transmits 7 bit ASCII encoded data 7 bit wo
13. ndemnify RLC against damages claims and expenses arising out of subsequent sales of RLC products or products containing components manufactured by RLC and based upon personal injuries deaths property damage lost profits and other matters which Buyer its employees or sub contractors are or may be to any extent liable including without limitation penalties imposed by the Consumer Product Safety Act P L 92 573 and liability imposed upon any person pursuant to the Magnuson Moss Warranty Act P L 93 637 as now in effect or as amended hereafter No warranties expressed or implied are created with respect to The Company s products except those expressly contained herein The Customer acknowledges the disclaimers and limitations contained herein and relies on no other warranties or affirmations Red Lion Controls BV Basicweg 11b NL 3821 BR Amersfoort Tel 31 0 334 723 225 Fax 31 0 334 893 793 Red Lion Controls AP 31 Kaki Bukit Road 3 06 04 05 TechLink Singapore 417818 Tel 65 6744 6613 Fax 65 6743 3360
14. ot necessary to separate the rear cover from the main circuit card 2 Locate the option card connector for the type of option card to be installed Hold the unit by the rear connector not the display board when installing an option card 3 Install the option card by aligning the option card connector with the slot bay in the rear cover The cards are keyed by position with different main board connector locations Be sure the connector is fully engaged and the tab on the option card rests in the alignment slot on the display board 4 Slide the assembly back into the case Be sure the rear cover latches fully into the case 5 Apply the option card label to the bottom side of the meter Do not cover the vents on the top surface of the meter The surface of the case must be clean for the label to adhere properly Apply the label to the area designated by the large case label TOP VIEW Alignment _ Slots Main ul Circuit il I Board pel Analog Output or Real Time Clock Card Serial i Setpoint Communications i Output Card A Card Finger Finger Hold bhd J eee ICICI EAI MAIN LABEL SERIAL ANALOG SETPOINT OUTPUT OUTPUT OR OUTPUT CARD REAL TIME CARD LABEL CLOCK CARD LABEL LABEL ORDERING INFORMATION DESCRIPTION RS485 Serial Communications Output Ca
15. rd length is sufficient to request and receive data from the meter PARITY BIT come Odd EUER no dd Set the parity bit to match that of the other serial communications equipment used The meter ignores the parity when receiving data and sets the parity bit for outgoing data If no parity is selected with 7 bit word length the meter transmits and receives data with 2 stop bits For example 10 bit frame with mark parity Print Print Input Print Total Options Value Value Print Max Print Setpoint amp Min Values Values METER ADDRESS Addr 0 to 99 S g Enter the serial node address With a single unit on a bus an address is not needed and a value of zero can be used RS232 applications Otherwise with multiple bussed units a unique address number must be assigned to each meter The node address applies specifically to RS485 applications ABBREVIATED PRINTING Abru A YES no YES Select abbreviated transmissions numeric only or full field transmission When the data from the meter is sent directly to a terminal for display the extra characters that are sent identify the nature of the meter parameter displayed In this case select AB When the data from the meter goes to a computer it may be desirable to suppress the node address and mnemonic when transmitting In this case set this parameter to YE5 PRINT OPTIONS OPES YES AD S ng Y
16. rd with Terminal Block PART NUMBER PAXCDC10 Extended RS485 Serial Communications Output Card with Dual RJ11 Connector RS232 Serial Communications Output Card with Terminal Block PAXCDC1C PAXCDC PAXCDC20 Extended RS232 Serial Communications Output Card with 9 Pin D Connector PAXCDC2C SPECIFICATIONS PAXH Isolation For Both Cards Isolation To Sensor Common 1400 Vrms for min Working Voltage 125 V Isolation To User Input Common 500 Vrms for 1 min Working Voltage 50 V RS485 Communication Card Type RS485 multi point balanced interface Isolation To Sensor amp User Input Commons 500 Vrms for min Working Voltage 50 V Not Isolated from all other commons Baud Rate 300 to 19 2k Data Format 7 8 bits odd even or no parity Bus Address 0 to 99 max 32 meters per line Transmit Delay Selectable 2 50 msec or 50 100 msec RS232 Communication Card Type RS232 half duplex Isolation To Sensor amp User Input Commons 500 Vrms for min Working Voltage 50 V Not Isolated from all other commons Baud Rate 300 to 19 2k Data Format 7 8 bits odd even or no parity WIRING CONNECTIONS RS232 Communications RECEIVING DEVICE PAX METER DTE DB25 DB25 DBO DCE DIE DIE Do E RXD Do 2 5 gt lt 73 RXD TXD 1 lt 3 7 3 7 4 COMM 5 7 5 WY Nc WY Terminal Block Connection Figure PIN 2 TX PIN 3 RX
17. red lion Tel 1 717 767 6511 Fax 1 717 764 0839 www redlion net Bulletin No PAXCDC E Drawing No LP0402 Released 3 05 MODEL PAXCDC SERIAL COMMUNICATIONS PLUG IN OPTION CARDS DESCRIPTION This bulletin serves as a guide for the installation configuration and operation of the RS232 and RS485 cards for the PAX family of meters Only one communication card can be used at a time The PAX meter can be fitted with up to three different option cards The slot bays of the option cards are dedicated to a particular card function The option card functions are serial communications analog output and setpoint output Only one card from each function category can be installed into the meter INSTALLING AN OPTION CARD Caution The option and main circuit cards contain static sensitive VAN components Before handling the cards discharge static charges from your body by touching a grounded bare metal object Ideally handle the cards at a static controlled clean workstation Also handle the cards by the edges only Dirt oil or other contaminants that may contact the cards can adversely affect circuit operation A N Warning Exposed line voltage exists on the circuit boards Remove all power to the meter AND load circuits before accessing the unit 1 Remove the main assembly from the rear of the case Squeeze the finger holds on the rear cover or use a small screwdriver to depress the side latches to release it from the case It is n
18. window of 50 msec minimum and 100 msec maximum This allows sufficient time for the release of the sending driver on the RS485 bus Terminating the command line with results in a response time window t of 2 msec minimum and 50 msec maximum The faster response time of this terminating character requires that sending drivers release within 2 msec after the terminating character is received At the beginning of time interval t3 the meter responds with the first character of the reply As with t the time duration of t3 is dependent on the number of characters and baud rate of the channel t3 10 of characters baud rate At the end of t3 the meter is ready to receive the next command The maximum serial throughput of the meter is limited to the sum of the times t4 t3 and t3 Communication Format Data is transferred from the meter through a serial communication channel In serial communications the voltage is switched between a high and low level at a predetermined rate baud rate using ASCII encoding The receiving device reads the voltage levels at the same intervals and then translates the switched levels back to a character The voltage level conventions depend on the interface standard The table lists the voltage levels for each standard INTERFACE STATE RS232 RS485 mark idle TXD RXD 3 to 15 V a b lt 200 mV space active TXD RXD 3 to 15 V a b gt 200 mV Voltage levels at the Receiver
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