1.25g CWDM SFP - 40Gb/s QSFP + ER4, 40km 1310nm SFP Transceiver JHA-QC40 - JHA
1.25g CWDM SFP - 40Gb/s QSFP + ER4, 40km 1310nm SFP Transceiver JHA-QC40 - JHA Nthuav:
Nta:
◊ 4 CWDM kab MUX/DEMUX tsim
◊ Mus txog 11.2Gbps ib channel bandwidth
◊ Sib sau ua ke bandwidth ntawm> 40Gbps
◊ Duplex LC connector
◊ Ua raws li 40G Ethernet IEEE802.3ba thiab 40GBASE-ER4 Standard
◊ QSFP MSA ua raws
◊ APD yees duab ntes
◊ Mus txog 40 km kis tau tus mob
◊ Ua raws li QDR / DDR Infiniband cov ntaub ntawv tus nqi
◊ Ib leeg +3.3V fais fab mov ua haujlwm
◊ Built-in digital diagnostic functions
◊ Kub ntau yam 0 ° C txog 70 ° C
◊ RoHS Ua Raws Cai
Daim ntawv thov:
◊ Rack rau khib
◊ Data centers Hloov thiab Routers
◊ Metro networks
◊ Hloov thiab Routers
◊ 40G BASE-ER4 Ethernet Txuas
Nqe lus piav qhia:
JHA-QC40 yog ib qho transceiver module tsim rau 40km optical kev sib txuas lus daim ntawv thov. Tus qauv tsim yog ua raws li 40GBASE-ER4 ntawm IEEE P802.3ba tus qauv. Lub module hloov 4 inputs channel (ch) ntawm 10Gb / s cov ntaub ntawv hluav taws xob rau 4 CWDM optical signals, thiab multiplexes rau hauv ib qho channel rau 40Gb / s optical kis tau tus mob. Reversely, nyob rau sab receiver, lub module optically de-multiplexes ib tug 40Gb / s input rau 4 CWDM channel signals, thiab converts lawv mus rau 4 channel tso zis hluav taws xob cov ntaub ntawv.
Lub hauv paus wavelengths ntawm 4 CWDM raws yog 1271, 1291, 1311 thiab 1331 nm raws li cov tswv cuab ntawm CWDM wavelength kab sib chaws txhais hauv ITU-T G694.2. Nws muaj ib tug duplex LC connector rau optical interface thiab 38-pin connector rau hluav taws xob interface. Txhawm rau txo qhov kev cuam tshuam ntawm qhov muag pom hauv qhov ntev-ntev, ib hom fiber ntau (SMF) yuav tsum tau siv rau hauv cov qauv no.
Cov khoom lag luam yog tsim los nrog cov qauv tsim, kev sib txuas kho qhov muag / hluav taws xob thiab digital diagnostic interface raws li QSFP Multi-Source Agreement (MSA). Nws tau raug tsim los ua kom tau raws li qhov kev ua haujlwm hnyav tshaj plaws nrog rau qhov kub thiab txias, av noo thiab EMI cuam tshuam.
Lub module ua haujlwm los ntawm ib qho +3.3V fais fab mov thiab LVCMOS / LVTTL thoob ntiaj teb kev tswj cov cim xws li Module Tam Sim No, Pib dua, cuam tshuam thiab Tsawg Fais Fab Hom muaj nyob nrog cov modules. Lub 2-xaim serial interface muaj nyob rau xa thiab tau txais kev tswj cov teeb meem nyuaj thiab kom tau txais cov ntaub ntawv kuaj mob digital. Cov kab ke ntawm tus kheej tuaj yeem hais tau thiab cov channel tsis siv tau tuaj yeem raug kaw kom tsim tau qhov yooj yim tshaj plaws.
JHA-QC40 yog tsim los nrog cov qauv tsim, kho qhov muag / hluav taws xob sib txuas thiab digital diagnostic interface raws li QSFP Multi-Source Agreement (MSA). Nws tau raug tsim los ua kom tau raws li qhov kev ua haujlwm hnyav tshaj plaws nrog rau qhov kub thiab txias, av noo thiab EMI cuam tshuam. Lub module muaj kev ua haujlwm siab heev thiab kev sib koom ua ke, siv tau los ntawm ob-xaim serial interface.
•Qhov siab tshaj qhov ntsuas
Parameter | Cim | Min. | Hom | Max. | Chav tsev |
Cia kub | TS | -40 |
| +85 | °C |
Cov khoom siv hluav taws xob | VCCT, R | -0.5 |
| 4 | V |
txheeb ze humidity | RH | 0 |
| 85 | % |
•Pom zooKev ua haujlwm ib puag ncig:
Parameter | Cim | Min. | Hom | Max. | Chav tsev |
Case kev khiav hauj lwm kub | TC | 0 |
| +70 | °C |
Cov khoom siv hluav taws xob | VCCT, R | +3.13 | 3.3 | + 3.47 | V |
Cov khoom siv tam sim no | KuvCC |
|
| 1000 | mA |
Lub zog Dissipation | PD |
|
| 3.5 | IN |
•Cov yam ntxwv hluav taws xob(TON = 0-70 °C, VCC= 3.13-3.47V
Parameter | Cim | Min | Hom | Max | Chav tsev | Nco tseg |
Cov ntaub ntawv tus nqi ib Channel |
| - | 10.3125 Nws | 11.2 | Gbps |
|
Kev siv fais fab |
| - | 2.5 | 3.5 | IN |
|
Cov khoom siv tam sim no | Icc |
| 0.75 ib | 1.0 | A |
|
Tswj I/O Voltage-High | HIV | 2.0 |
| Vcc | V |
|
Tswj I / O Voltage-Low | YOG | 0 |
| 0.7 | V |
|
Inter-Channel Skew | TSK |
|
| 150 | Ps |
|
RESETL Duration |
|
| 10 |
| Peb |
|
RESETL De-ua pov thawj lub sijhawm |
|
|
| 100 | ms |
|
Hwj chim Nyob Sijhawm |
|
|
| 100 | ms |
|
Transmitter | ||||||
Single Ended Output Voltage kam rau ua |
| 0.3 |
| 4 | V | 1 |
Common hom Voltage kam rau ua |
| 15 |
|
| mV |
|
Transmit Input Qhov txawv voltage | PEB | 150 |
| 1200 | mV |
|
Transmit Input Qhov txawv Impedance | CEEB TOOM | 85 | 100 | 115 |
|
|
Data Dependent Input Jitter | DDJ |
| 0.3 |
| UI |
|
Tus txais | ||||||
Single Ended Output Voltage kam rau ua |
| 0.3 |
| 4 | V |
|
Rx Output Qhov txawv voltage | Vo | 370 | 600 | 950 ua | mV |
|
Rx tso zis nce thiab poob Voltage | Tr/Tf |
|
| 35 | ps | 1 |
Tag nrho Jitter | TJ |
| 0.3 |
| UI |
|
Nco tseg:
- 20~80%
•Optical Parameters(TOP = 0 to 70°C, VCC = 3.0 ~ 3.6V)
Parameter | Cim | Min | Hom | Max | Chav tsev | Ref. |
Transmitter | ||||||
Txoj Haujlwm Wavelength | L0 | 1 264.5 | 1271 ib | 1277.5 ib | nm |
|
L1 | 1 284.5 | 1291 ib | 1297.5 ib | nm |
| |
L2 | 1 304.5 | 1311 | 13 17.5 | nm |
| |
L3 | 13 24.5 | 1331 ib | 1 337.5 | nm |
| |
Sab-hom Kev Tiv Thaiv Kev Sib Tw | SMSR | 30 | - | - | dB |
|
Total Average Launch Power | PT | - | - | 8.3 | dBm ib |
|
Nruab Nrab Launch Power, txhua txoj kab |
| -3 | - | 5 | dBm ib |
|
TDP, txhua txoj kab | TDP |
|
| 2.3 | dB |
|
Extinction Ratio | YOG | 3.5 | 6.0 |
| dB | |
Transmitter Eye Mask Definition {X1, X2, X3, Y1, Y2, Y3} |
| {0.25, 0.4, 0.45, 0.25, 0.28, 0.4} |
| |||
Optical Return Poob Tolerance |
| - | - | 20 | dB |
|
Nruab nrab Launch Fais Fab OFF Transmitter, txhua txoj kab | Poof |
|
| -30 | dBm ib |
|
Kwv tij siv suab nrov | Kuj |
|
| -128 | dB/HZ | 1 |
Optical Return Poob Tolerance |
| - | - | 12 | dB |
|
Tus txais | ||||||
Kev puas tsuaj | THd | 3 |
|
| dBm ib | 1 |
Nruab Nrab Lub Hwj Chim ntawm Txais Cov Khoom Siv, txhua txoj kab | R | - nees nkaum ib |
| -6 | dBm ib |
|
Tau txais hluav taws xob 3 dB sab sauv Txiav tawm zaus, txhua txoj kab |
|
|
| 12.3 | GHz |
|
RSSI qhov tseeb |
| -2 |
| 2 | dB |
|
Txais Reflectance | Rrx |
|
| -26 | dB |
|
Txais Lub Hwj Chim (OMA), txhua txoj kab |
| - | - | 3.5 | dBm ib |
|
Tau txais hluav taws xob 3 dB sab sauv Cutoff zaus, txhua txoj kab |
|
|
| 12.3 | GHz |
|
LOS De-Assert | LUBD |
|
| -25 | dBm ib |
|
LOS Assert | LUBA | -35 |
|
| dBm ib |
|
LOS Hysteresis | LUBH | 0.5 |
|
| dB |
|
Nco tseg
- 12dB Reflections
•Diagnostic Monitoring Interface
Kev tshuaj ntsuam xyuas digital muaj nuj nqi muaj nyob ntawm txhua QSFP + ER4. Lub 2-xaim serial interface muab cov neeg siv kev sib cuag nrog module. Cov qauv ntawm lub cim xeeb yog qhia nyob rau hauv ntws. Qhov chaw nco tau teem rau hauv qis dua, ib nplooj ntawv, chaw nyob ntawm 128 bytes thiab ntau nplooj ntawv chaw nyob sab saud. Cov qauv no tso cai rau lub sijhawm nkag mus rau qhov chaw nyob hauv nplooj ntawv qis dua, xws li Interrupt Flags thiab Monitors. Tsawg lub sij hawm tseem ceeb nkag, xws li serial ID cov ntaub ntawv thiab qhov chaw pib, muaj nyob rau ntawm nplooj ntawv xaiv muaj nuj nqi. Qhov chaw nyob interface siv yog A0xh thiab feem ntau yog siv rau lub sijhawm tseem ceeb cov ntaub ntawv xws li kev cuam tshuam kev tuav kom thiaj li pab tau ib zaug-nyeem ntawv rau tag nrho cov ntaub ntawv ntsig txog qhov teeb meem cuam tshuam. Tom qab muaj kev cuam tshuam, IntL tau lees paub, tus tswv tsev tuaj yeem nyeem tawm ntawm tus chij teb los txiav txim siab txog cov channel cuam tshuam thiab hom chij.
EEPROM Serial ID Memory Contents (Ahh)
Cov ntaub ntawv Chaw nyob | Ntev | Lub npe ntawm Ntev | Nqe lus piav qhia thiab cov ntsiab lus | |
Base ID Fields | ||||
128 | 1 | Tus cim | Identifier Hom serial Module (D = QSFP +) | |
129 | 1 | Ext. Tus cim | Extended Identifier ntawm Serial Module (90 = 2.5W) | |
130 | 1 | Txuas | Code ntawm connector hom (7 = LC) | |
131-138 : kuv | 8 | Specification ua raws | Code rau electronic compatibility lossis optical compatibility (40GBASE-LR4) | |
139 | 1 | Encoding | Code rau serial encoding algorithm (5 = 64B66B) | |
140 | 1 | BR, npe | Nominal ntsis tus nqi, units ntawm 100 MBits / s (6C = 108) | |
141 | 1 | Tus nqi txuas ntxiv xaiv Kev Ua Raws Cai | Cim npe rau ncua tus nqi xaiv ua raws | |
142 | 1 | Ntev (SMF) | Txuas ntev txhawb rau SMF fiber ntau hauv km (28 = 40KM) | |
143 | 1 | Ntev (OM3 50um) | Txuas ntev txhawb rau EBW 50/125um fiber ntau (OM3), units ntawm 2m | |
144 | 1 | Ntev (OM2 50um) | Txuas ntev txhawb rau 50/125um fiber ntau (OM2), units ntawm 1m | |
145 | 1 | Ntev (OM1 62.5um) | Txuas ntev txhawb rau 62.5 / 125um fiber ntau (OM1), units ntawm 1m | |
146 | 1 | Ntev (Copper) | Txuas ntev ntawm tooj liab lossis active cable, sib sau ua ke ntawm 1m Txuas ntev txhawb nqa rau 50/125um fiber ntau (OM4), units ntawm 2m thaum Byte 147 tshaj tawm 850nm VCSEL raws li tau teev tseg hauv Table 37 | |
147 | 1 | Ntaus tech | Cov cuab yeej siv tshuab | |
148-163 : kuv | 16 | Tus neeg muag khoom npe | QSFP + tus neeg muag khoom lub npe: TIBTRONIX (ASCII) | |
164 | 1 | Ntxiv Module | Ntxiv Module codes rau InfiniBand | |
165-167 : kuv | 3 | Vendor YOG | QSFP + tus neeg muag khoom IEEE tuam txhab ID (000840) | |
168-183 : kuv | 16 | Tus neeg muag khoom PN | Qauv Zauv: JHA-QC40 (ASCII) | |
184-185 : kuv | 2 | Vendor Rev | Hloov kho qib rau ntu tus lej muab los ntawm tus neeg muag khoom (ASCII) (X1) | |
186-187 : kuv | 2 | Wave length los yog Copper cable Attenuation | Nominal laser wavelength (wavelength = tus nqi / 20 hauv nm) lossis tooj liab cable attenuation hauv dB ntawm 2.5GHz (Adrs 186) thiab 5.0GHz (Adrs 187) (65A4 = 1301) | |
188-189 : kuv | 2 | Wavelength kam rau ua |
Guaranteed ntau ntawm laser wavelength (+/- tus nqi) los ntawm nominal wavelength. (wavelength Tol.=value/200 in nm) (1C84=36.5) | |
190 | 1 | Max cas temp. | Qhov ntsuas kub siab tshaj plaws hauv degrees C (70) | |
191 | 1 | CC_BASE | Tshawb xyuas cov lej ID hauv paus (chaw nyob 128-190) | |
Extended ID teb | ||||
192-195 : kuv | 4 | Kev xaiv | Rate Select, TX Disable, Tx Fault, LOS, Warning indicators for: Temperature, VCC, RX, power, TX Bias | |
196-211 : kuv | 16 | Tus neeg muag khoom SN | Serial tooj muab los ntawm tus neeg muag khoom (ASCII) | |
212-219 : kuv | 8 | Hnub Caiv | Vendor's producering date code | |
220 | 1 | Diagnostic Monitoring Hom | Qhia seb hom kev tshuaj ntsuam xyuas twg yog siv (yog tias muaj) hauv Module. Ntsis 1,0 Reserved (8 = Lub Hwj Chim Nruab Nrab) | |
221 | 1 | Txhim kho kev xaiv | Qhia seb qhov kev xaiv ua kom zoo dua qub yog siv rau hauv Module. | |
222 | 1 | Khaws tseg | ||
223 | 1 | CC_EXT | Tshawb xyuas code rau Extended ID Fields (chaw nyob 192-222) | |
Tus neeg muag khoom tshwj xeeb ID Fields | ||||
224-255 : kuv | 32 | Vendor Specific EEPROM |
•Sijhawm rau Soft Control thiab Status Functions
Parameter | Cim | Max | Chav tsev | Cov xwm txheej |
Lub Sijhawm pib pib | t_ ib | 2000 | ms | Lub sij hawm los ntawm lub hwj chim on1, kub plug los yog nce ntug ntawm Reset kom txog rau thaum lub module yog tag nrho functional2 |
Pib dua Init Assert Time | t_reset_init | 2 | μs | Kev Pib dua yog tsim los ntawm qib qis ntev dua li qhov tsawg kawg nkaus rov pib dua lub sij hawm tam sim no ntawm ResetL tus pin. |
Serial Bus Hardware Npaj Sijhawm | t_serial | 2000 | ms | Lub sij hawm los ntawm lub hwj chim on1 mus txog rau thaum module teb rau cov ntaub ntawv kis tau tus mob tshaj 2-xaim serial tsheb npav |
Saib Xyuas Cov Ntaub Ntawv NpajSijhawm | t_data | 2000 | ms | Lub sij hawm los ntawm lub hwj chim on1 rau cov ntaub ntawv tsis npaj, ntsis 0 ntawm Byte 2, deasserted thiab IntL asserted |
Pib dua lub sij hawm Assert | t_rov | 2000 | ms | Lub sij hawm los ntawm nce ntug ntawm ResetL tus pin kom txog rau thaum lub module ua haujlwm tag nrho2 |
LPMode Assert Sijhawm | ton_LPMode | 100 | μs | Lub sij hawm los ntawm kev lees paub ntawm LPMode (Vin: LPMode = Vih) kom txog thaum lub zog siv hluav taws xob nkag mus rau qib qis zog |
IntL Assert Sijhawm | ton_IntL | 200 | ms | Lub sij hawm los ntawm qhov tshwm sim ntawm qhov tshwm sim ua rau IntL mus txog Vout: IntL = Vol |
IntL Lub Sijhawm Deassert | toff_IntL | 500 | μs | toff_IntL 500 μs Lub Sijhawm los ntawm meej ntawm kev nyeem 3 kev ua haujlwm ntawm tus chij cuam tshuam txog Vout: IntL = Voh. Qhov no suav nrog lub sijhawm deassert rau Rx LOS, Tx Fault thiab lwm yam khoom chij. |
Rx LOS Assert Time | ton_los | 100 | ms | Lub sij hawm los ntawm Rx LOS lub xeev mus rau Rx LOS ntsis teeb thiab IntL tau lees paub |
Chij Assert Time | ton_flag | 200 | ms | Lub sij hawm los ntawm qhov tshwm sim ntawm qhov tshwm sim ua rau tus chij rau cuam tshuam chij me ntsis teeb thiab IntL tau lees paub |
Mask Assert Sijhawm | ton_mask | 100 | ms | Lub sij hawm los ntawm daim npog qhov ncauj me ntsis set4 kom txog rau thaum cuam tshuam IntL kev lees paub yog inhibited |
Mask De-asserted Sijhawm | toff_mask | 100 | ms | Lub sij hawm los ntawm daim npog me ntsis cleared4 kom txog rau thaum cuam tshuam IntlL cov haujlwm rov pib dua |
ModSelL Assert Sijhawm | ton_ModSelL | 100 | μs | Lub sij hawm los ntawm kev lees paub ntawm ModSelL mus txog rau thaum module teb cov ntaub ntawv xa mus rau 2-xaim serial tsheb npav |
ModSelL Lub Sijhawm Deassert | toff_ModSelL | 100 | μs | Lub sij hawm los ntawm deassertion ntawm ModSelL mus txog rau thaum lub module tsis teb rau cov ntaub ntawv kis tau tus mob tshaj 2-xaim serial tsheb npav |
Power_over-ride los yogFais fab-set Assert Time | ton_Pub | 100 | ms | Lub sij hawm los ntawm P_Down ntsis teeb 4 kom txog rau thaum module fais fab mov nkag mus rau qis zog theem |
Power_over-ride lossis Power-set De-assert Time | toff_Pub | 300 | ms | Lub sij hawm los ntawm P_Down me ntsis cleared4 mus txog rau thaum lub module yog tag nrho functional3 |
Nco tseg:
1. Fais fab tuag yog txhais raws li qhov tam sim no thaum cov khoom siv hluav taws xob ncav cuag thiab nyob twj ywm ntawm lossis siab dua tus nqi qis kawg nkaus.
2. Kev ua haujlwm siab yog txhais raws li IntL asserted vim cov ntaub ntawv tsis npaj me ntsis, ntsis 0 byte 2 de-asserted.
3. Ntsuas los ntawm kev poob moos tom qab nres me ntsis ntawm kev nyeem ntawv pauv.
4. Ntsuas los ntawm kev poob moos tom qab nres me ntsis ntawm kev sau ntawv pauv.
•Transceiver Block Diagram
•Pin Assignment
Daim duab ntawm Lub Rooj Tswjhwm Saib Cov Khoom Txuas Thaiv Tus lej PIN thiab Lub Npe
•PinKev piav qhia
Pin | Logic | Cim | Lub npe / piav qhia | Ref. |
1 |
| GND | Hauv av | 1 |
2 | CML-I | Tx2n | Transmitter Inverted Data Input |
|
3 | CML-I | Tx2p | Transmitter Non-Inverted Data output |
|
4 |
| GND | Hauv av | 1 |
5 | CML-I | Tx4n | Transmitter Inverted Data Output |
|
6 | CML-I | tx4 p | Transmitter Non-Inverted Data Output |
|
7 |
| GND | Hauv av | 1 |
8 | LVTTL-I | ModSelL | Module Xaiv |
|
9 | LVTTL-I | ResetL | Module Pib dua |
|
10 |
| VccRx | + 3.3V Fais Fab Txais Txais | 2 |
11 | LVCMOS-I/O | SCL | 2-Wire Serial Interface Clock |
|
12 | LVCMOS-I/O | SDA | 2-Wire Serial Interface Cov ntaub ntawv |
|
13 |
| GND | Hauv av | 1 |
14 | CML-O | rx3 pab | Receiver Inverted Data Output |
|
15 | CML-O | Rx 3 n | Receiver Non-Inverted Data Output |
|
16 |
| GND | Hauv av | 1 |
17 | CML-O | Rx 1 p | Receiver Inverted Data Output |
|
18 | CML-O | Rx 1 n | Receiver Non-Inverted Data Output |
|
19 |
| GND | Hauv av | 1 |
20 |
| GND | Hauv av | 1 |
nees nkaum ib | CML-O | Rx 2 n | Receiver Inverted Data Output |
|
nees nkaum ob | CML-O | rx2 pab | Receiver Non-Inverted Data Output |
|
nees nkaum peb |
| GND | Hauv av | 1 |
nees nkaum plaub | CML-O | Rx 4 n | Receiver Inverted Data Output |
|
25 | CML-O | rx4 pab | Receiver Non-Inverted Data Output |
|
26 |
| GND | Hauv av | 1 |
27 | LVTTL-O | ModPrsL | Module Present |
|
28 | LVTTL-O | IntL | cuam tshuam |
|
29 |
| VccTx | + 3.3V Fais Fab Transmitter | 2 |
30 |
| Vcc1 | + 3.3V Fais fab mov | 2 |
31 | LVTTL-I | LPMode | Tsawg zog hom |
|
32 |
| GND | Hauv av | 1 |
33 | CML-I | Tx3p | Transmitter Inverted Data Output |
|
34 | CML-I | Tx3n | Transmitter Non-Inverted Data Output |
|
35 |
| GND | Hauv av | 1 |
36 | CML-I | tx1 p | Transmitter Inverted Data Output |
|
37 | CML-I | Tx1n | Transmitter Non-Inverted Data Output |
|
38 |
| GND | Hauv av | 1 |
Nco tseg:
- GND yog lub cim rau ib leeg thiab cov khoom siv (lub zog) ntau rau QSFP modules, Txhua yam muaj nyob rau hauv QSFP module thiab tag nrho cov module voltages raug xa mus rau qhov muaj peev xwm txwv tsis pub sau. Txuas cov no ncaj qha mus rau tus tswv tsev lub teeb liab lub dav hlau hauv av. Laser output disabled ntawm TDIS > 2.0V los yog qhib, enabled ntawm TDIS
- VccRx, Vcc1 thiab VccTx yog tus txais thiab xa hluav taws xob xa hluav taws xob xa khoom thiab yuav tsum tau siv ua ke. Pom zoo host board power supply filtering yog qhia hauv qab no. VccRx, Vcc1 thiab VccTx tuaj yeem txuas nrog sab hauv hauv QSFP transceiver module hauv kev sib xyaw ua ke. Cov pins txuas yog txhua qhov ntsuas rau qhov siab tshaj plaws tam sim no ntawm 500mA.
•Pom zoo Circuit Court
•Mechanical Dimensions
Product details duab:
Yam khoom Guide:
Peb qhov kev txhim kho yog nyob ntawm cov cuab yeej zoo tshaj plaws, cov txuj ci zoo heev thiab txuas ntxiv dag zog rau cov thev naus laus zis rau Kev Muag Khoom Zoo Tshaj 1.25g CWDM SFP - 40Gb/s QSFP + ER4, 40km 1310nm SFP Transceiver JHA-QC40 - JHA, Cov khoom yuav muab rau thoob plaws ntiaj teb, xws li: Ixayees, Barcelona, Fabkis, Yuav kom ua tiav peb lub hom phiaj ntawm cov neeg siv khoom ua ntej thiab kev sib raug zoo hauv kev koom tes, peb tsim ib pab neeg ua haujlwm engineering thiab pab pawg muag khoom los muab kev pabcuam tag nrho kom txaus siab rau peb cov neeg siv khoom. Zoo siab txais tos koj los koom tes nrog peb thiab koom nrog peb. Peb yog koj qhov kev xaiv zoo.
Los ntawm Alice los ntawm Mali - 2017.09.16 13:44
Ib tus neeg muag khoom zoo hauv kev lag luam no, tom qab kev nthuav dav thiab kev sib tham ua tib zoo, peb tau txais kev pom zoo pom zoo. Cia siab tias peb koom tes ua ke.
Los ntawm Janice los ntawm Swiss - 2017.10.13 10:47