DCP - Interface. Dynavert L. Technical Description July 2010 (Draft) Dynavert

Transcription

1 DCP - Interface Dynavert L Technical Description July 2010 (Draft) Dynavert

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3 Introduction 1 Main characteristics 2 DCP Interface for Dynavert L Technical Description (Draft) Protocol including position set value, position actual value and communications Physical definition of the interface 3 Protocol description 4 Sequence timing 5 Dealing with transmission faults 6 4BS

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5 1. Introduction This document describes the Drive Control and Position (DCP) protocol used for the serial connection between a lift controller and lift automatic control equipment. The DCP protocol enables Drive Control, i.e. full control of automatic control equipment and Drive Position control, i.e. position control through transmission of position set values and position actual values, and scanning of all control equipment actual values and parameters. The DCP protocol also enables parametrizing of the automatic control equipment. The serial connection using this protocol thus replaces all the hardwire links between the controller and the automatic control equipment. The protocol also makes it possible to customise lift travel for any distance between floors. 2. Main characteristics The protocol is designed for a half duplex RS485 interface link. This is a point-topoint connection between the lift controller and the control equipment. The controller operates as a master unit while the control equipment operates as a slave unit. This means that the control equipment only responds to incoming messages from the controller. In order to prevent hazardous situations from arising in the event of a major fault (e.g. an interruption in the link), the control equipment must be equipped with a timeout watchdog. When the timeout time elapses, the system will automatically switch to a safe condition. The protocol operates with three types of travel commands: A) Trip with constant brake distance as per the current travel commands In this operating mode, control of the control equipment is similar to that used in the conventional methods using a parallel connection. Here, a series of travel commands (v1, v2, etc.) correspond to different terminal speeds settings on the control equipment. Activating the travel command starts the trip, de-activating the command sets the braking point. Another binary signal is used for the stop switch in order to ensure precise stopping just before the flush level. Other binary signals are used for setting the direction of travel and for fine adjustment. In this operating mode, the positions of the braking point and the stopping point are detected by conventional shaft devices (e.g. contactors or photocells) or an absolute encoder position measuring system. The data provided by these methods is converted into the necessary binary signals by the lift controller. 4BS Page 5 of 20

6 B) Floor-to-floor trip with variable travel In this operating mode, the travel distance (in mm) required is transmitted to the control equipment over the interface before the trip begins. When the travel command is activated, the trip starts and the control equipment must travel the exact distance that has been communicated to it. The travel command can be deactivated at any time but this will have no effect on travel. It is quite simple therefore to program as many floor-to-floor trips as required. For a floor-to-floor trip no information from the shaft devices are required. The control equipment must be in a position to travel the various distances of floor-to-floor trips in the optimum time. C) Trip with variable travel In this operating mode the required travel distance is communicated to the control equipment. Changes to the travel distance are possible under certain marginal conditions even during the trip. In this operating mode the control equipment uses the previously travelled lift car travel provided by the controller (over the interface) as the position actual value. This means that the lift controller must be equipped with an absolute encoder position measuring system. The position actual value must have a minimum resolution of 1 mm. With this operating mode it is possible to travel to any destination from any point in the lift shaft and to change the destination during the trip. A typical trip covering several floors would consist of the following steps (a trip which passes a floor must use the operating mode trip type 2 "Floor-to-floor trip with variable travel"): a) Before the trip starts, (e.g. with the lift stopped at floor no. 1), the control equipment receives a travel distance in the form of a position set value. Normally the travel distance to the next floor but one (i.e. floor no. 3 in our example) is used. b) The travel command is given and the trip starts. c) If the controller has established that a stop at floor no. 3 is not required, it will transmit a new position set value (e.g. floor no. 4) to the control equipment. The travel distance is measured from the starting point of the trip (i.e. floor no. 1). The control equipment will ignore the old position set value and will travel to the new destination. This procedure can be repeated as many times as required. If the controller has established that a stop is required at floor no. 3, then no further action from the controller is required. As soon as the control 4BS Page 6 of 20

7 equipment reaches the braking point, it automatically starts the braking procedure. The control equipment then calculates the braking point from the position set value and the position actual value at the current speed. When a new position set value is given, care must be taken that the braking point for the previously valid travel distance value has not been reached at the moment when the new value is transmitted. When the control equipment receives a new position set value, it checks immediately if the braking point can still be reached. If the point has not yet been reached, the value is accepted. If acceptance is not possible, the previous value will be maintained. The control equipment transmits a signal back to the controller indicating whether it has accepted the new value or not. 3. Physical definition of the interface Level: RS485 Plug connector: 5-pin, pluggable screw terminal (e.g.. Phoenix MSTB ): Pin 1 Shield, Pin 2 RS485 A, Pin 3 RS485 B, Pin 4 GND (optional), Pin 5 +12V max. load rating l 50 ma, not short-circuit-proof (optional) The shield is earthed to the ground (GND) A 120 Ohm terminating resistor can be fitted between pin 2 and pin Protocol description The basic structure of the protocol is as follows: Each message consists of a fixed number of bytes. User data length is not transmitted. The protocol is designed for a point-to-point link. The lift controller is the 'active' partner (the master). The control equipment is the 'passive' partner, (the slave), i.e. it responds to a message from the controller within a set time. The device address is not transmitted. A checksum byte at the end of each message ensures a high degree of data security. 4BS Page 7 of 20

8 The protocol enables: rapid transmission of the control commands, status signals and the position actual value; communications with the control equipment at a slower speed for control equipment parameterizing and for interrogation of special actual values. Only one byte of the message is used for the slower communications channel. This channel is driven by its own protocol, a communications protocol. Each message transmits one byte of communications data. The remaining bytes in the message are used for the transmission of rapid data and thereby constitute the process data channel. The protocol consists of the following parts: 4.1. Message from the lift controller to the control equipment: The message consists of 5 bytes. A complete, standard message looks like this: Command Position actual value Communications Checksum When a new trip type is transmitted, the message looks like this: Command 00H Trip type Communications Checksum When a new position set value is transmitted, the message looks like this: Command Position set value Checksum Commands: The command byte contains the information listed below. A pre-set bit activates the corresponding command. Bit 0: Bit 1: Bit 2: Bit 3: Bit 4: Bit 5: Bit 6: Bit 7: Controller release Drive command Stop switch Fine adjustment trip Direction DOWN Trip type transmission Position set value transmission Fault in last response message Bit 0: Controller release When this bit is not set, the control equipment will remain locked out. The lift car will be held with the mechanical brake. If this bit is removed during a trip, the control equipment will be locked out immediately and the mechanical brake will operate. 4BS Page 8 of 20

9 Bit 1: Drive command The drive command bit activates a trip on condition that the controller enable command has been given. The control equipment will activate the travel protection and the brake and then start the trip. The control equipment will use the last trip type transmitted by the controller. The time at which the drive command is de-activated is only relevant with trip type no. 1. In this case, the time at which the drive command is de-activated sets the braking point. With all other trip types, the drive command must be de-activated at a set time before the end of the trip in order to prevent the control equipment from starting a new trip. Bit 2: Stop switch The stop switch acts as a correction point for position detection as long as the position actual value is not given by the interface. The signal is activated before or at the same time as the drive command is set and is de-activated when the stop switch is reached. This bit is only relevant for trip type no. 1 (trip with constant braking distance as per the current travel commands). With all other trip types this bit will not be read. Bit 3: Fine adjustment trip This command activates a fine adjustment trip. The control equipment will travel at the very slow fine adjustment speed for the duration of the signal. Bit 4: Direction DOWN This command sets the direction of travel of the lift. If the command is de-activated, the lift will travel upwards. If the command is activated, the lift will travel downwards. Any changes to the direction of travel during a trip will be ignored by the control equipment. Bit 5: Trip type transmission This bit is activated to indicate that the message is transmitting information about the trip type and that byte 3 of the message indicates the trip type (see trip type). Bit 6: Position set value transmission This bit is activated to indicate that the message is transmitting information about the position set value and that the bytes from 2 to 4 indicate the position set value (see position set value). Bit 7: Fault in last response message This bit is activated when the controller detects a checksum fault in the last message from the control equipment to the controller. The controller will therefore ignore the last message. This means that the control equipment must send the communication byte again in the next message. The new, current values for the remaining data will be transmitted. In this case the controller must send the change in the position actual value since the last valid transmission between the controller and the control equipment with the special response message used in these cases. 4BS Page 9 of 20

10 Position actual value Bit 5 and bit 6 of the first message byte are set = 0 to indicate that the 2 nd nd 3 rd bytes are transmitting the position actual value. The 2nd and 3rd bytes contain the changes in travel distance since the last valid transmission of a position actual value. Transmitting the travel distance changes only has the advantage that large distance can be transmitted using word variables. The direction of the change is displayed by plus or minus signs in front of the value (UP = plus sign, DOWN = minus sign) in two's complement representation (1st byte = High-Percentage, 2nd byte = Low-Percentage). Position changes are transmitted in mm (value range from mm to mm) Note: During transmission of the position actual values the controller must check that the rounding error is not added. A special procedure would, for example, add the newly transmitted position actual value (since the start of the trip) to the controller. The position actual value is always transmitted as the difference between the total measured travel (from the absolute encoder position measuring system) and the sum of the travel distance sent so far. Position set value Bit 6 of the first message byte is set = 1 to indicate that the 2 nd, 3 rd and 4 th bytes are transmitting the position set value. The position set value is always set at the start of travel. This value is always positive (1 st byte = High-Percentage, 3 rd Byte = Low-Percentage) and is transmitted in mm. The value range is from 0 to mm. The controller must ensure that the transmission of the position set value is completed at least 20 ms before the corresponding deceleration point has been reached, i.e. the response message from the control equipment must already have been received by the controller. The response message from the control equipment must also indicate whether or not the new position set value has been accepted (see 4.2). Trip type Bit 5 of the first message byte is set = 1 to indicate that the 3rd byte is transmitting the trip type. The byte can be set to the following values: 0 Inspection at speed vr 1 V1 Trip with constant braking distance, speed V1 2 V2 Trip with constant braking distance, speed V2 3 V3 Trip with constant braking distance, speed V3 4 V4 Trip with constant braking distance, speed V4 5 V5 Trip with constant braking distance, speed V5 6 V6 Trip with constant braking distance, speed V6 7 V7 Trip with constant braking distance, speed V7 8 V8 Trip with constant braking distance, speed V8 9 Floor trip Floor trip with variable distance 10 Trip with variable distance 11 Inspection trip vr1 Inspection at speed v1 12 Inspection trip vr2 Inspection at speed v2 13 Inspection trip vr3 Inspection at speed v3 4BS Page 10 of 20

11 Communication Bit 5 and bit 6 of the first message byte are set = 0 to indicate that this byte is transmitting the data for the communication channel. This channel can be used to set all the actual values and parameters of the control equipment. The communication channel is driven by its own protocol (see 4.3). Checksum The checksum is the XOR link element for the four data bytes Message from control equipment to the lift controller: The message consists of 3 bytes. A complete message looks like this: Status Communication Checksum Status: The status byte contains the following information: Bit 0: Bit 1: Bit 2: Bit 3: Bit 4: Bit 5: Bit 6: Bit 7: Control equipment ready Trip active Pre-warning active Common fault active Levelling speed low Position set value or trip type accepted blank Fault in last message received Bit 0: Control equipment ready This indicates that no faults are present and that the minimum delay time after a trip has elapsed. The control equipment is ready for a new trip. Bit 1: Trip active The control equipment is currently performing a trip. Changes in the direction of travel are no longer possible. Bit 2: Pre-warning active The control equipment is in a critical conditions (e.g. the heat sink is just below the shut-down limit). A trip which has already been started can be finished. After this the system must wait until no further pre-warning messages are active. 4BS Page 11 of 20

12 Bit 3: Common fault active A control equipment monitoring function has triggered. The control equipment has been shut down, the travel contactor has been de-activated and the brake has been deenergized. Bit 4: Levelling speed low The levelling speed has reached or dropped below the setting on the control equipment. The control equipment continuously monitors the current travel speed against a set limit value (the levelling speed). When travel speed drops below this limit, bit 4 will be set. This function enables simple monitoring of the levelling speed (e.e. at the end stops) by the controller. Bit 5: Position set value or trip type accepted This bit is only relevant when the last message from the controller to the control equipment has transmitted a new trip type or position set value. A response message containing this bit indicates that the control equipment has accepted the new value just received. Transmission of new trip type: A new trip type will not be accepted during a active trip. Trip type 3 (Trip with variable travel) will only be accepted when the position actual value has been transmitted over the serial interface. Transmission of new position set value: A new set value will only be accepted: when the current trip is a short distance trip with variable travel or a trip with variable travel. when the trip is a floor-to-floor trip with variable travel which has not yet started when the trip is a variable trip which has sufficient residual distance and the stop point requested can be reached with the trip curve parameter settings. In all other cases the old position actual value will be used. Bit 7: Fault in last message received This bit is set when the control equipment has detected a fault (e.g. checksum fault) in the last message from the controller to the control equipment. The control equipment will therefore ignore the last message because it is faulty. This means that the controller must send the communication byte or the position set value again with the next message. The new, current values for the remaining data will be transmitted. In the case of a position actual value, the controller must send the difference in travel which has occurred since the last valid message from the control equipment to the controller with the corresponding valid response message. 4BS Page 12 of 20

13 Communication: This bit transmits the data for the communications channel. This channel can be used to set all the actual values and parameters of the control equipment. The communications channel is driven by its own protocol (see 4.3). Checksum: The checksum is the XOR link element for both data bytes 4.3. Data communication channel: Introduction The data communications channel is subordinate to the real time data channel and is driven by its own protocol. One communications data byte is transmitted with each message. The communications channel can also be used to set the actual value and the parameters of the control equipment. In order to do this, the data exchange between the internal display and the internal keypad of the control equipment must be redirected over the DCP interface to the display and keypad of the lift controller. In order to perform this operation (i.e. redirect the control equipment internal display and keypad data over the interface), the contents of the communications data must not be defined in the DCP protocol since only the current display characters and keypad information is to be transmitted. The following marginal conditions must also be observed: Protocol If the communication channel is not transmitting any data, the Byte 00H indicating this condition must be transmitted. The control equipment will not send any data until it receives the following command sequence from the controller: (STX) (1FH) (ETX) On reception of this command sequence, the control equipment will send the display data (or the changes on the display). From this point onwards, the controller will send the key code for the key pressed. When the controller wishes to end the communication, it will send the following command sequence. (STX) (01H) (ETX) On reception of this command sequence, the control equipment will stop sending data over the communication channel (00H). For standard configurations, the lift controller must have at least one display with two lines of 20 characters each. The DCP protocol will support up to four lines; this option must be agreed with the suppliers. 4BS Page 13 of 20

14 Data communications from the controller to the control equipment The communications message looks like this: (STX) (1F) (keypad code) (ETX) The keypad coding is as follows: Bit Function 0 Blank 1 Reset (of control equipment fault messages) 2 Status (reset display to output status) 3 Down 4 Up 5 Enter 6 F1 (Function key 1, function depends on the control equipment) 7 F2 (Function key 2, function depends on the control equipment) 4BS Page 14 of 20

15 Data communication from the control equipment to the controller The communication message looks like this: (STX) (1FH) (Line) (Cursor position) (Character 1)...(Character n) (ETX) (Line) (Cursor position) (Character 1) ( Character n) Control character for the output line (see control character table) Control character for the cursor position (see control character table) Sequence of characters after the cursor position, to be shown on the display (see character set below). The codes from 00H to 1FH are used as control characters and have the following meaning: Code (Hex) Description 0 Communication channel to idle state 1 Stop communication 2 STX = Start communication message 3 ETX = End communication message 4 Output in line 1 of display 5 Output in line 2 of display 6 Output in line 3 of display 7 Output in line 4 of display 9 Cursor position 1 0A Cursor position 2 0B Cursor position 3 0C Cursor position 4 0D Cursor position 5 0E Cursor position 6 0F Cursor position 7 10 Cursor position 8 11 Cursor position 9 12 Cursor position Cursor position Cursor position Cursor position Cursor position Cursor position Cursor position Cursor position 17 1A Cursor position 18 1B Cursor position 19 1C (blank) 1D (blank) 1E (blank) 1F Message identifier for communication message 4BS Page 15 of 20

16 Character set for display data The table below shows the character set used; the table is based on the character set used by most commercial display units. Blank bytes should not be used if possible. 2.H 3.H 4.H 5.H 6.H 7.H 8.H 9.H A.H B.H C.H D.H E.H F.H.0H (Blank) P \ p * ).1H! 1 A Q a q * ) ä.2h 2 B R b r 2 * ).3H # 3 C S c s 3 * ).4H $ 4 D T d t * ).5H % 5 E U e u * ) Ü.6H & 6 F V f v * ).7H 7 G W g w * ).8H ( 8 H X h x.9h ) 9 I Y i y -1.AH * : J Z j z.bh + ; K [ k {.CH, < L l.dh - = M ] m }.EH. > N ^ n.fh /? O _ o ö *) These characters are not usually included in the character set of LCD displays. They must be loaded into the programmable CG-RAM. The following codes can be used for this purpose: 1FH 04H 0EH 15H 04H 04H 04H 00H (Arrow upw ards w ith limit) 04H 04H 04H 15H 0EH 04H 1FH 00H (Arrow dow nw ards w ith limit) 2 0CH 02H 04H 08H 0EH 00H 00H 00H (Squared) 3 0CH 02H 0CH 02H 0CH 00H 00H 00H (Cubed) 04H 0EH 1FH 04H 04H 04H 04H 00H (Arrow upw ards) 04H 04H 04H 04H 1FH 0EH 04H 00H (Arrow dow nw ards) 04H 0EH 1FH 04H 04H 1FH 0EH 04H (Double arrow ) 02H 05H 15H 0EH 04H 04H 04H 00H 4BS Page 16 of 20

17 5. Sequence timing: The interface is a half duplex interface and the driver for this type of interface must therefore have directional commutation. In order to prevent collisions, the sequence used must be accurately timed. A cycle time (the time the message takes to travel from the controller to the control unit and back again) of 10 ms is also required. The sequence is as follows: Baudrate = 19,200 Baud, 8-bit data length, no parity, 1 stop bit. Switching off of the transmission driver 0.5 ms (max.) after transmission of the last bit. Earliest possible transmission start after reception of a message: 0.6 ms (controller + control equipment). Latest possible controller transmission start after reception of a message: 3 ms. Latest possible control equipment transmission start after reception of a message: For the transmission of the position actual value, the interface is linked to a control loop. In these circumstances it is advisable to transmit the data at the same, regular intervals (in this case 10 ms). The following method should be used. The control equipment must process the interface program every 10 ms (with a time-controlled interrupt). This method will, however, only guarantee a maximum response time of 10 ms. If the controller sends the next message up to a maximum of 3 ms after reception of a message, the complete message will automatically be transmitted from the controller to the control equipment and back again within 10 ms. This means that the controller is automatically synchronised with the timing code of the control equipment. It is important therefore that the controller does not exceed a maximum response time of 3 ms. Message from lift controller Message from control equipment (inverter) Time-controlled interrupts in control equipment (10 ms) 1. Telegramm min. 0.6 ms max. 3.0 ms min. 0.6 ms max. 3.0 ms min. 0.6 ms max. 3.0 ms min. 0.6 ms max. 3.0 ms min. 0.6 ms max. 3.0 ms 6. Dealing with transmission faults 4BS Page 17 of 20

18 In order to prevent transmission faults from falsifying or losing position actual and set values, the behaviour of the controller and the control equipment in the event of transmission faults must be precisely defined Behaviour of controller in the event of transmission faults (viewed from the controller) There are two basic types of transmission faults: 1) The controller detects a checksum fault when receiving a response message from the control equipment. Reaction: The type of message (transmission of position actual value, trip type or position set value) must be retained, i.e. the message type of the previous message must be repeated. The current values are transmitted as a command. Bit 7 is set to indicate a response message fault. The position actual value is taken as the total change in travel since the last, valid complete message cycle (i.e. the last cycle in which the message was transmitted from the controller to the control equipment and back again without fault). This value is transmitted. Communication of the last transmitted byte is repeated. The last value for the position set value or the trip type is repeated. The status byte of the control equipment is ignored. 2) The status bit 7 (Fault in last response message) is set in the response message sent by the control equipment to the controller. Reaction: The type of message (transmission of position actual value, trip type or position set value) must be retained, i.e. the message type of the previous message must be repeated. The current values are transmitted as a command. The position actual value is taken as the total change in travel since the last, valid complete message cycle (i.e. the last cycle in which the message was transmitted from the controller to the control equipment and back again without fault). This value is transmitted. Communication of the last transmitted byte is repeated. The last value for the position set value or the trip type is repeated. 4BS Page 18 of 20

19 6.2. Behaviour of control equipment in the event of transmission faults (viewed from the inverter) 1. The control equipment detects a checksum fault in a message received from the controller. Reaction: The control equipment ignores the message and sends a response message with the following content: Status of the current value, bit 7 is set to indicate a message fault. A zero byte (00H) is sent as communication. 2: The command bit 7 (Fault in last response message) is set in the message sent by the controller to the control equipment. Reaction The command is processed following the normal procedure. Position set value In the event of a checksum fault in the last transmission from the controller to the control equipment, the position actual value transmitted will be used. In all other cases the position actual value of the last valid message will be subtracted from the position actual value transmitted. Communications In the event of a checksum fault in the last transmission from the controller to the control equipment, the communications byte will be processed as normal. In all other cases it will be ignored. Position set value In the event of a checksum fault in the last transmission from the controller to the control equipment, the travel set will be processed as normal. In all other cases the result of the checksum procedure will be transmitted in Status Bit 5 (Position set value accepted) in the response message. Trip type This will be processed as normal. 4BS Page 19 of 20

20 DCP- Interface for Dynavert L - Technical description 4BS LOHER GmbH A Siemens Company Servicezentrale: PO-Box Ruhstorf Servicecenter: Hans-Loher-Str Ruhstorf Fax.: +49 (0) Tel.: +49-(0) Fax.: +49 (0) Fax.: +49 (0) h - hotline.: +49 (0) lift@loher.com service.sys@loher.com