SE-1000-3现货 in stock! 欢迎来电咨询~！！

SE-1000-3,

SE-1000-3

有福之州-福州聚福兴供应进口工业控制系统成套备件：DCS PLC模块卡件，底板机架机槽，CPU模块，输入输出模块，模拟量模块，电源模块，通讯模块，工业交换机，触摸屏人机界面显示器，插头连接器，连接电缆接插电缆，伺服控制器，电机马达，伺服驱动器，驱动板电源板电路板，采集卡，影像卡，工控机，示教器，工业机器人配件..........
有福之州-福州聚福兴供应自动化供应进口品牌：罗克韦尔AB， Prosoft，西门子SIEMENS，施耐德SCHNEIDER，通用电气GE FANUC， 发那科FANUC，安川Yaskawa，欧姆龙Omron，三菱Mitsubishi，基恩士Keyence，东方步进Vexta，迈创Matrox，美家仪器NI，研华Advantech，莫迪康Modicon，思科Cisco，大隈Okuma，瑞士ABB，力士乐 Bosch Rexroth，台达Delta，福克斯波罗Foxboro，富士Fuji，霍尼韦尔Honeywell，惠普Hp，瑞恩 Reliance...........

欢迎咨询~~~~~

　摘要：波峰焊是将熔融的液态焊料，借助与泵的作用，在焊料槽液面形成特定形状的焊料波，插装了元器件的PCBA置与传送链上，经过某一特定的角度以及一定的浸入深度穿过焊料波峰而实现焊点焊接的过程。作为一种传统的焊接技术，目前波峰焊依然在电子领域发挥着积极作用，所以波峰焊机器设备的智能化和节能越来越重要。本案例使用顾美触摸屏PLC一体机，全自动控制控制波峰焊工艺，使生产流程更加简洁，工艺更加优化，节能和智能化。
　　一.原理
　　按照工艺流程，通过PLC编程控制波峰焊设备各个工位运作，在有产品到达喷雾位置或波峰位置的时候，自动启动喷雾和波峰，并可以实时采集温度到PLC中，再通过PLC传到触摸屏上实现实时温度监控，并可以实时监控各个工位部件的运作状态。
　　二.优势
　　与传统的工艺具有以下优点：
　　1.能精确的控制锡炉的开关时间，提前熔锡，解决了用户在使用过程中去定时打开锡炉和关闭锡炉的问题，这套系统还为客户设计了三个定时的开关锡炉的时间，按照正常上班，周末上班，其他定时开关锡炉，能有效的为客户节省电费和时间。
　　2.本系统自带4路模拟量输入功能，能有效的实时监控预热温度，锡炉温度作用，并设有自动保护功能，在锡炉熔锡温度没有到达设定温度时不能手动自动启动波峰，对产品实施了保护功能。
　　3.在全自动状态下，喷雾和波峰都由产品来控制，当有产品到达喷雾位置时，控制系统自动启动喷雾，并且可以根据产品宽度手动设置喷雾速度，当产品完成喷雾时自动关闭喷雾，再有产品来时再次启动;当产品到达波峰位置时自动启动波峰，产品焊接完成自动关闭波峰(可手动设置)。节省了助焊剂和电能，真正达到节能作用!
　　4.手动状态下，可以手动开启关闭各个原件，可以有效的调机和查找问题。
　　5.参数设置;在参数设置的画面里，可以设置传动运输速度，自动喷雾速度，生产产量，自动开关锡炉时间，定期维护时间等，可根据要求添加。
　　6.本系统具有自动计数功能，可以统计产品的数量，并可以设定产量，当到达产量是自动发出信号，提醒客户计数到达。
　　7.本系统还有具有维护时间到期提醒，通过设定维护时间定期提醒客户维护，从而增加机器的使用寿命。
　　8.本系统还具有密码锁机功能;在这套系统共设置五期的定期锁机功能，可供客户自己选择，时间一到期自动停止机器运行，解决了客户收款难问题。
　　9.自动报警功能，当温度过高或过低自动报警。
　　三.控制系统
　　配置可编程控制器与触摸屏一体机，把波峰焊的性能智能化、自动化、人性化变成现实，具有稳定性高、功能丰富、操作简单、使用方便、控制灵活等优点配置有4路模拟量输入2路模拟量输出可以对多路温度进行监控。
　　四.操作性能
　　1.触摸屏可中英文显示，具有丰富的显示功能，将波峰焊的各个工位运行状态和采集到锡炉熔锡的温度、加热器工作状态、当前时间、报警信息等准确直观的显示出来。简单的通过手指点击触摸屏进行操作设置，并可查核、设定和修改各种调节参数，实现人机对话，易懂、易学、易记，操作简单、方便。
　五.综合特点
　　1.采用可编程控制器跟触摸屏PLC一体机，锅炉的运行状态清晰可见。所有操作都简单地通过点击触摸屏轻松完成，锅炉控制器的超级显示功能、控制功能十分齐全。
　　2.能全自动的启动喷雾，喷雾完成后，自动关闭喷雾，节省了原料;全自动波峰可以自动控制波峰的起落，节省了电能!达到了节省原料节省能源的功效。
 

SC-N10 380VAC/220A 110KW 110V . 220V AC 2NO+2NC

1747-L542 SLC 5/04处理器模块 32K内存 DH+和DH-485/RS232口

USB-8476

EmCORE-i413A

HIOKI 2211C710

JEVSA-YV250

FB2502

TFT-LCM MXS1210

1492-JG70 IEC 1-Ckt Feed-Through Grd Blk 70mm

1492-WM4 IEC Term Blck 8x47.6x41mm Screw

软启动器 3RW44231BC46

BC647CSCEMK QuickPanel Control software with Proficy GlobalCare Complete and a hardware key

GC647IFPLSRUNLMT GCC iFIX Plus SCADA Unlmt Srv

IC200CBL655 Mitsubishi Fx 25-pin, RS-422 Cable to DataPanel 45/65/85

IC646MPSS99 Logic Developer PLC Standard Unlimited Seat Site License

IC647IFSTDV00075K iFIX Standard HMI 75 I/O Development (M1 Kit Part)

IC670ALG310 Analog Output, Voltage, 8 Channel, +/-10V, 0 to 10V

IC697CPU782RR CPU, 16 MHz, 12K Discrete I/O, Expandable Memory, Floating Pt

IC800PSHV045 PSM-45HVi 45 kW high voltage power supply kit for Alpha servos

ControlLogix/1756 System 1756-OV32E 10-30 VDC ELEC FUSED SINKING OUTPUT 32 PT (36 PIN)

Industrial Computers 6182H-10KRH4D VVCE 1000, KEYPAD, STD MEM, ENET, DC

Process Control 1757-FIMEXP100 FOUNDATION FIELDBUS FIM MODULE EXPANSION

Operator Interface 2711P-RDB7C PV PLUS 700, KEY/TOUCH SCREEN DISPLAY MODULE

Support 9355-WABDER SUPT REINSTATEMENT CONTRACT FOR 9355WABDE

Support 9351-WESRTR SUPT REINSTATEMENT CONTRACT FOR 9351WESRT

ControlNet Products 1747-KFC15 SLC CNET SERIAL INTERFACE MODULE

RSI Software Products 9301-2SE2400ITE RSVIEW32 WORKS 32K (ITALIAN)

RSI Software Products 9355-WABOEMEU1R UPGRADE: OUT-SUPT: WINLINX TO RSLINX OEM CD

Motion Control MPL-A320P-HJ22AA MOTOR,SERVO,2.94NM,5000RPM,ENCDR,230V,4.0KG

Motion Control 2090-U3AE-D4409 CABLE,TWO AXISTO LOGIX 1756MOAE2 CARD,9M

CBL-119-1 Cable.SIMATIC T.I. 305 DCU (RS-422)

IC5105KAX0000 Panel C Industrial Computer 15" Unbundled with WIN XP

IC800PCUBC10S050 PowerCube Flying Lead Interface Cable, 1000 Steps/Rev & Power Save Enabled, 5 Meters

OC647IFESGDV00300C iFIX Optn: ESig & ERec 300 I/O Development (M1Component Part)

20AD027A3AYNANC0 PowerFlex 70 AC Drive 27 A at 20 Hp 20A

20DC385N0ENNBNANE PowerFlex 700S AC Drive 20D

20L-GH30-A1 Hose Kit,(2)30 Ftx1 In. Dia.,W/ Fittings

25C-FAN2-INT PowerFlex 527 Control Internal Fan Kit

280-PWRM22C-M1 ArmorStart Three-Phase Power Media

FX2N-64MT 主机32入/32出?晶体管输出

6ES7953-8LJ00-0AA0 MMC 512K

DAQCard-AO-2DC

MIC-2732

MOXA CP-168U

超微 P8SCT

RPC-600/610

EC3-1811LDNA

PIO-16/16L(PCI)H

1492-SPM3B020-N MCB Supplementary Protector 2 A

软启动器 3RW40241TB04

AD641ECL321 ECLiPS Programming Software for the Series 90-30 SLP with OnTOP

GC646PME001 GlobalCare Complete for PCM Machine Edition Version 1 User

HE800ACC116 Cage-clamp (screw) style I/O plug, 16-terminal. (Qty 10)

IC640BVB317RR Video Board for FactoryMaster

IC647HSTSSEO1750KM eSignature Option for Historian - Standard Server 1,750,000 Points (M4 Key)

IC660BLM508 Bus Terminator 75 Ohm (Qty 4)

IC695CMX128 Control Memory Xchange Module 128Megbytes of user shared memory.

IC756WET200E-22 Custom Datasource Toolkit, English, Version 2.2

CompactLogix System D1769-UM004AENP COMPACT THERMOCOUPLE MOD.

PLC-5/1771 System D1771-6.5.119 U.MNL.INTRINSICALLY SAFE

Process Control 1757-FIMRTPBASE FIELDBUS INTERFACE RTP BASE

Operator Interface 2711P-B7C6D1 PV PLUS 700, KEY/TOUCH, RIO/DH, DC PS, STD MEM

Support 6500-PS7PTS SUPT RENEWAL CONTRACT FOR 6500PS7PT

Support 9358-PLTMCLTR SUPT REINSTATEMENT CONTRACT FOR 9358PLTMCLTENE

Support F1785-KA3 FIRMWARE UPGRADE FOR 1785-KA3 COMMUNICATION MODULE

RSI Software Products 9301-2SE2200U1R UPGRADE: OUT-SUPT: RSVIEW WORKS 150 TO 300

RSI Software Products 9701-VWSB000JPU2 RSV SE STATION 100 - UNLTD DISP UPGRADE (JAPANESE)

RSI Software Products 9399-EDS2TUT RSWIRE TUTORIAL/BASIC OVERVIEW

Motion Control 2098-DSD-005X-DN DRIVE, 2.5A/7.5A, ULTRA3000 W/DEVICENET/INDEX

BC5002TBW0000 12 Inch Inbligence Industrial Computer - Bundled - Perbance Series - w/ Windows 2000

IC300CBF005 FOX Fiber Cable Pair, 5.0M

IC752DTX550 DataPanel 55. Same as DataPanel 50 except display is brighter VF type

MTR-3S43-G-R-B-C-SRR Servo Motor 24V Brake Nemz56C with Seal

ZA06B-6089-H106 Alpha series SVU1-130 amplifier rated 130 amps and 200/230 VAC

20BE6P1A0AYNANC0 PowerFlex 700 AC Drive 6.1 A 5 Hp 20B

20G14TC650JN0NNNNN PowerFlex 755 AC Packaged Drive

25-RF056-EL PowerFlex 520 56A 230V EMC Filter Kit

2711P-RYKS PanelView Plus 7 Accessory

FRN 3 7P11S-4CX 5 7 KVA 75A 37KW 3相AC380V/50Hz/60Hz

AR22JR-3A11B 三位钥匙开关 1开1闭

ATV-58HD54N4 37

VXI-PCIe-8362T

DAQ-2010

NEAT-405

GA-EP45T-UD3LR

JMB-4811CLDNA

ROCKY-3732EVS-R2

1492-SPM1B130 MCB Supplementary Protector 13 A

直流电源 6EP1332-1SH42 100/240VAC 输入，24VDC/2.5A 输出

20AC015A3AYNACC0 PowerFlex 70 AC Drive 20A

GA647TPD150 Proficy GlobalCare Assist for CIMPLICITY HMI ProServer 150 I/O Development and Runtime System

GP647IFPRRNUNLMT GCP iFIX Profsnl SCADA Unlmt Run

IC600CB504RR Internal Memory Control Mdl (for use in Model 600 or 6000)

IC647HSTCS20KM Historian Enterprise Corporate Server 20000 Points (M4 Key)

IC647TSSRV001 Proficy Troubleshooter 1 User Server License

IC693PWR330 Power Supply, 120/240 Vac, 125 Vdc, High Capacity. Battery not include d. Battery is now included in the CPU backplane box.

IC756MDV010K-98 DV Draw Dvlpnt on Alpha OpenVMS, Korean, Version 9.8

MicroLogix 1000/1761 System D1761-6.2 MICROLOGIX 1000 W/HAND-HELD PROG (HHP) MANUAL

PLC-5/1771 System 1771-NT2 HIGH RESOLUTION ISOLATED ANALOG MODULE

Distributed I/O 1794-ADN DEVICENET ADAPTER WITH 24V DC POWER SUPPLY

Communications 9352-WABGW WINTELLIGENT LINX GATEWAY

Operator Interface D6190-6.5.3DE CONTROLVIEW MOUSE GRAFIX EDITOR USER MANUAL(GERMAN

Support 9358-BA30S SUPT RENEWAL CONTRACT FOR 9358BANT30ENE

Support 9392-CDRSZHU UPGRADE TO ENGLISH/CHINESE BUNDLE

RSI Software Products 9324-RL01U3DEER UPGRADE: OUT-SUPT: GERMAN RS500 STARTER TO RS500

RSI Software Products 9301-2SE3500U4R UPGRADE: OUT-SUPT: RSVIEW32 RUNTIME 150 TO 100K

RSI Software Products 9356-STD2350U1 UPGRADE: IN-SUPT: RSSQL STD 150 TO STD 5000 TAG

Motion Control Y-1003-1-H00AA MOTOR,SERVO,0.35 NM,4500RPM,ENCDR,115V,1.04KG

5004D-24 Obsolete - Message Center. 2 Line, 11MM, Green VFD. NEMA 4

IC200CHS121 I/O INTERPOSING FUSE STYLE, 16 PT

IC694MDL752 OUTPUT MODULE 5/24 VDC (TTL) 0.5AMP 32 POINT NEGATIVE LOGIC

MSI-WEB-2 Web or Excel Reporting Clients 2 Pack

VSPCSE-ANLYST50 VisualSPC SE Analyst, 50 license pack.

20BD052A0NYNACC1 PowerFlex 700 AC Drive 52 A 40 Hp 20B

20G11LC1K4JN0NNNNN PowerFlex 755 AC Packaged Drive

22D-E012N104 PowerFlex 40P 7.5 kW (10 Hp) AC Drive

140ESI06210 Quantum ASCII 接口模块, RS232, 2通道

291D-FAP-G1 Direct Online Reversing Starte

MY2NJ-D2 NEW 24VDC，有反向二极管，2开2闭，触点5A.中国制

1756-M14 LOGIX5555? 3.5M内存

PXIe-4082

PCI-7250

TC-PCIC01

ACE-832AP-RS

PM-1033

CBP-3064

1492-PD31123 380 A Power Distribution Block

中央机架 6ES7403-1TA01-0AA0 ER1 机架，18 槽，只能插信号模板

2097-F2 Kinetix 300/350 10.0 A Line EMI Filter

EDS-308-SS-SC-T C1 D2 6-port 10/100, 2 port single-mode SC fiber (-40 to 75 deg C op temp)

GFK-1503 Manual VersaMax PLC

IC220ACC201 RELAY MODULE ISOLATION SET (REQUIRES 1 IC220TBK206)

IC647CBL708 Cable, Workstation Intf. to Series Six CPU, Parallel, 10 feet

IC647PRTORAM Proficy Portal Oracle Connector (M4 Key)

IC693DSM302 DSM302 motion controller module

IC756ADV001J-99 DV Development - AIX Op Sys Addt'l User, Japanese, Version 9.9

MSI-IGC 7 Day x 24 Hour Support / GlobalCare

SLC/1746 System 1746-RT33 REPLACEMENT TERMINAL BLOCK

Distributed I/O 1738-OB4EM12 24VDC 4 SOURCING OUTPUTS WITH M12 CONNECTORS

Communications 1784-CP11 CABLE ASSY, 10FT/3.20M, IBM XT OR COMPATIBLE CMPTR

Operator Interface 2711-NP1 REPLACEMENT MOUNTING CLIPS

Support 9302-RTS SUPT RENEWAL CONTRACT FOR 9302RT

Support 9324-RL5300FRS SUPT RENEWAL CONTRACT FOR 9324RL5300FR

DeviceNet Products 2706-P43R INVIEW MESSAGE DISPLAY. 1 LINE, 20 CHARACTERS

RSI Software Products 9301-2SE335DEU1R RSVIEW32 RUNTIME 150-5K UPGRADE OUT-SUPT (DE)

RSI Software Products 9326-AD5WDENE WIRING DIAGRAM GENERATOR ADD-ON 5 USER

Motion Control MPG-A010-091S24 MOTOR,SERVO,GEAR RATIO 91,35NM,65RPM,SINGL,BRK

Silver Series 1785-V40L VME PLC-5/40 CONTROLLER W/EXT. LOCAL PORT

HE693PWR524 Power supply adapter for Series 90-30 to allow for redundant power supplies.

IC660BRD024 Genius 32point 12/24 Vdc Source Block for Redundancy "T" Configuration

QPICBDE0000 10.4" Color TFT, Blank Label, Ethernet, CF Card, 24VDC, UL, cUL, CE, UL1604

ST-5232 STXi Serial Interface module RS-485, 2 Channels

20BC1P3A3AYNANC0 PowerFlex 700 AC Drive 20B

20F1ANC140AA0NNNNN PowerFlex 753 AC Packaged Drive

22B-A5P0N104 PowerFlex 40- 0.75 kW (1 HP) AC Drive

140DDI36400 Quantum 开关量 DC 输入, 64点, 24 VDC, 6组隔离

284D-FVD4P0B-10-RR-3-DB-SB-EMI DeviceNet Variable Frequency Drive

E3JM-DS70M4T 70cm,扩散反射式,触点输出3A带ON/OFF延时?电源同上

ADAM-5000/485 基于RS-485的分布式数据采集控制系统

PXI-2544

W26361-W10-Z2-02-36

Hivertec HPCI-CPD534A

PCI-1756

FI-RBXAT-PEL02Z/4 FI-RBXAT-PEL02/3

PCI-9016

1492-MCAA220 20 A UL489 Miniature Circuit Breaker

1494U-LA36 1494U 30A-60A Aluminum Lugs

软启动器 3RW44552BC45

CBL-30-BT-10 Brake cable for MTR-3S or MTR-3N series servo motors with brake. 10 feet

GF-0200/MTI Connecting FlashCable to Chicago Dial Indicator Logic Series, Zipper c ompatible.

IC200TBX140 Tool box, Micro 40 and software. Includes (IC200UDR140) 24VDC In/Relay Out, requires 120/240VAC power, (IC200USB001) RS-232 option board with (2) 0 -10VDC analog in with Proficy software, manuals and cables (IC646MPM101)

IC646TBSPMPS400 Smart Process Monitoring Process+ server 400 loops

IC647NSE000 CIMPLICITY HMI SMARTEYE Driver

IC693ACC330 Base is discontiued. Use generic TBQC base IC693ACC329.

IC752BUU000 WinCfg & DataPanel Software Upgrade

IC800VMCP100 Power cable for 100 W to 750 W VersaMotion servo motors- 10 meter

SLC/1746 System 1746-OW16 RELAY OUTPUT MODULE FOR PROGRAMMABLE CONTROLLER

Industrial Computers 6189V-35HDD 3.5" HARD DISK DRIVE STANDARD

Application-specific products 1400-PD51A POWERMONITOR DISPLAY MODULE

Operator Interface 2711-B6C20L1 PV600 COLOR KEY&TOUCH, ENET & RS232 PRINT

Support 9301-2SE2400DER SUPT REINSTATEMENT CONTRACT FOR 93012SE2400DE

Support 9307-EM83PXS SUPT RENEWAL CONTRACT FOR 9307EM83PXENE

DeviceNet Products 1734D-IB8XOW8S 24 VDC 8 SINK IN 8 RELAY OUT, DNET COMMS, SPRING

RSI Software Products 9301-2SE250PTU5R RSVIEW32 WORKS 5K-100K UPGRADE OUT-SUPT (PT)

RSI Software Products 9358-BNT60U2 UPGRADE: IN-SUPT: RSBATCH 10 TO 60

Motion Control MPL-B330P-MK22AA MOTOR,SERVO,4.18 NM,5000RPM,MULTI,460V

Motion Control 2090-U3BB2-DM44 BREAKOUT BOARD, CN1, ULTRA3000 DRIVE MOUNTED

GFK-0646 C Programmer's Toolkit for Series 90-70 User's Manual

IC646CCW000 CIMPLICITY Client for Microsoft Windows

MSCPX-21280698 Marathon Exp CPU - 333 MHz AMD CPU, 128M, 6G, Win98, 2 ISA and 2 PCI/ISA expansion slots

PSPC-DC50-220L Prof Shop Floor SPC DC 50 User 220v

20BC015A0AYYANC0 PowerFlex 700 AC Drive 20B

20F11FC043JA0NNNNN PowerFlex 753 AC Packaged Drive

2198-KITCON-DSL CONNECTOR KIT, K5500, DSL

2711P-RBK10 PanelView Plus Accessory

280-PWRM35H-M35 ArmorConnect 3-PH Power Media trnk cable

CQM1-ID214 输入32点. 24V DC

IPC-610P/250-14 PC总线工控机箱，9-ISA/1-CPU/4-PCI槽底板，带250瓦电源?。4U高度

PCI-6035E

Am5X86-P75-S

IPC-610H PCA-6006

ASUS华硕P5E64

LMB-868

BANDIT-VGA XR-M130-18500

1492-L10 IEC Term Blck 10x73.5x43.5mm Spr Clp

1492-XIM2024-16R Connection Products

软启动器 3RW44243BC44

BC647MPP010 Logic Developer PLC Professional 10 pack with Proficy GlobalCare Complete with USB Hardware key

GC647IFPRSR00900 GCC iFIX Profsnl SCADA 900 I/O Srv

IC200CHS101 I/O interposing disconnect style, 16 point

IC646MSP001 Logic Developer State Professional

IC647IFSTRN00075C iFIX Standard HMI 75 I/O Runtime (M1Component Part)

IC670CHS002 I/O Base, Box Style is obsolete. Recommend IC670CHS001 I/O Base, Barrier Style.

IC697CSE924RR State Logic CPU, 64MHz, 80486DX2

IC800SKCI010 Interface cable to connect an S2K auxiliary I/O connector to the 44A726268-001 terminal block. 1 meter

ControlLogix/1756 System 1756-OF8 ANALOG OUTPUT - CURRENT/VOLTAGE 8 PTS (20 PIN)

Industrial Computers 6182H-10TRH6D VVCE 1000, TOUCH, STD MEM, RIO/DH, DC

Process Control 1757-FIMUPG065 FIELDBUS LICENSE UPGRADE, 65 FIMS

Operator Interface 2711P-RGT10 PV PLUS/VVCE PROTECTIVE ANTIGLARE OVERLAYS QTY 3

Support 9355-WABOEMENR SUPT REINSTATEMENT CONTRACT FOR 9355WABOEMEN

Support 9354-SD101S SOFTWARE SUPPORT CONTRACT RENEWAL

ControlNet Products 1788-CNCR CNET LOGIX DAUGHTERCARD - REDUNDANT COAX MEDIA

RSI Software Products 9301-2SE2400KOU5 RSVIEW32 WORKS 5K-32K UPGRADE IN-SUPT (KO)

RSI Software Products 9355-WABSNEU3 UPGRADE: IN-SUPT: RSLINX SINGLE NODE TO RSLINX GW

Motion Control MPL-A330P-HK22AA MOTOR,SERVO,4.18NM,5000RPM,ENCDR,230V,5.0KG

Motion Control 2090-UXBC-D1515 BREAKOUT BOARD CABLE,CN2,ULTRAX000,15M

CBL-12-MPS-20 Power Cable, MTR-1221-*-D & MTR-1231-*-D Stepping Motor with S2K, 20 Ft.

IC600PB551RR PDT Video Board

IC800SKCBVL050 Power/Brake Cable, S2K to 4.5 - 5kW S-Series Servo Motors, 5 Meters

OC647IFESGRNUNLMTC iFIX Optn: ESig & ERec Unl I/O Runtime (M1Component Part)

20AD052A3AYNACC0 PowerFlex 70 AC Drive 52 A at 40 Hp 20A