一、定時器是干什么用的
定時器是一種用于定時和計時的機械或電子裝置,類似鬧鐘,發明于1876年,在此之前,人們通常會用沙漏或水漏進行定時或計時,那么定時器有什么用呢?
1、定(ding)(ding)時(shi)(shi)(shi)(shi)器(qi)的(de)(de)作用(yong)主要是幫助人們準確控制時(shi)(shi)(shi)(shi)間(jian),也能起到備(bei)忘的(de)(de)作用(yong),通過(guo)定(ding)(ding)時(shi)(shi)(shi)(shi)器(qi)設定(ding)(ding)好時(shi)(shi)(shi)(shi)間(jian),以便提示(shi)自己在規定(ding)(ding)的(de)(de)時(shi)(shi)(shi)(shi)間(jian)做某些事情,并在適當時(shi)(shi)(shi)(shi)間(jian)轉換事宜,比如玩多久(jiu)手(shou)機就(jiu)去工(gong)作或學習等。
2、除此之(zhi)外,隨著技(ji)術的(de)進步,定時器(qi)也廣(guang)泛應用(yong)于各(ge)種生活(huo)電器(qi),如開水機、熱水器(qi)的(de)定時控制,空調的(de)定時開關(guan)等,設置在電器(qi)上的(de)定時器(qi)能使電器(qi)定時開機、定時關(guan)機,實現節能、安(an)全(quan)、健康的(de)使用(yong)。
3、定時(shi)(shi)器還能應用于軍事方面,比如定時(shi)(shi)炸彈、定時(shi)(shi)雷管等(deng)都是通(tong)過定時(shi)(shi)器來控制的。
二、定時器的種類有哪些
起(qi)初的(de)定時(shi)器(qi)是(shi)利用機械鐘帶動(dong)開關的(de),隨著定時(shi)器(qi)的(de)發(fa)展,也有(you)了許多不(bu)同的(de)種類,那(nei)么定時(shi)器(qi)有(you)哪些種類呢?根據不(bu)同的(de)原(yuan)理(li)和(he)工作類型,定時(shi)器(qi)可(ke)分(fen)為:
1、斷開延時型定時器
這種定時(shi)(shi)(shi)器是當輸入條(tiao)件00000為ON時(shi)(shi)(shi)無(wu)延時(shi)(shi)(shi)作(zuo)用,只有(you)在輸入條(tiao)件00000為OFF時(shi)(shi)(shi)產生(sheng)延時(shi)(shi)(shi)作(zuo)用。它(ta)在SIEMENS的PLC中又被稱為SF型定時(shi)(shi)(shi)器。
2、接通延時型定時器
接通延時型(xing)定(ding)時器(qi)是各種(zhong)PLC中(zhong)常見的(de)基(ji)本的(de)定(ding)時器(qi),這種(zhong)定(ding)時器(qi)在(zai) SIEMENS的(de)PLC中(zhong),稱為SD型(xing)定(ding)時器(qi)。
3、保持型接通延時定時器
這種定時器(qi)又(you)(you)稱SS型定時器(qi),是當輸(shu)入條件(jian)00000為ON后(hou),即(ji)產生鎖存功(gong)能,即(ji)使(shi)輸(shu)入條件(jian)00000又(you)(you)變為OFF,仍視輸(shu)入條件(jian)為ON,當定時器(qi)的當前值(zhi)等于設定值(zhi)時,定時器(qi)動作。
4、脈沖型定時器
這種定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)是(shi)當輸入條(tiao)件00000為ON后,定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)即(ji)(ji)時(shi)(shi)(shi)動作,但(dan)經過(guo)定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)所(suo)設(she)定(ding)(ding)(ding)的(de)(de)時(shi)(shi)(shi)間(jian)后,即(ji)(ji)使輸入條(tiao)件00000仍為ON,定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)卻變為OFF狀(zhuang)態(tai)。即(ji)(ji)這種定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)ON狀(zhuang)態(tai)的(de)(de)維(wei)持(chi)時(shi)(shi)(shi)間(jian)是(shi)由設(she)定(ding)(ding)(ding)值決定(ding)(ding)(ding)的(de)(de)。如果00000為ON的(de)(de)時(shi)(shi)(shi)續(xu)時(shi)(shi)(shi)間(jian)小于定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)的(de)(de)設(she)定(ding)(ding)(ding)值,定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)的(de)(de)ON狀(zhuang)態(tai)維(wei)持(chi)時(shi)(shi)(shi)間(jian)為輸入條(tiao)件00000為ON的(de)(de)持(chi)續(xu)時(shi)(shi)(shi)間(jian)。這種定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)在SIEMENS的(de)(de)PLC中,稱為SP型定(ding)(ding)(ding)時(shi)(shi)(shi)器(qi)。
5、擴張型脈沖定時器
這種定(ding)(ding)時(shi)(shi)器(qi)與(yu)脈沖型(xing)定(ding)(ding)時(shi)(shi)器(qi)的(de)區別(bie)是,只要輸入條(tiao)件(jian)00000出現(xian)了(le)ON狀態(tai),不管其持續時(shi)(shi)間多長,均可使定(ding)(ding)時(shi)(shi)器(qi)為ON的(de)維持的(de)時(shi)(shi)間與(yu)定(ding)(ding)時(shi)(shi)器(qi)的(de)設定(ding)(ding)值一(yi)致。這種定(ding)(ding)時(shi)(shi)器(qi)在SIEMENS的(de)PLC中,稱為SE型(xing)定(ding)(ding)時(shi)(shi)器(qi)。