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继电器常识：
继电器有三个接线柱：常开(NO)，常闭(NC)，接地(C)
如果连接的时间长，偶尔需要断电， 那么接NC 和 C， 这样继电器set on 时为断电。除此之外，继电器还可以控制按键，以及长按。
继电器接通时，该继电器的灯会亮。ZZR08有8个继电器，以一个字节表示其整体状态，以每位的位高（bit high）代表对应继电器的状态。例如：第一个继电器set on 时为00000001，set off 时该位为0；第二个set on 时为00000010(2), set off 时该位为0。以此类推.
怎样使用继电器：
1. Command “ls /dev/tty*”, you can find like this
/dev/ttyRelayCard
在接入继电器之前运行“ls /dev/tty*”， 接入之后再运行一次，多出来的就是继电器的标识。
2. Check the file /etc/udev/rules.d/ACS.rules. In this file, there have a code like
this:
SUBSYSTEMS=="usb", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", SYMLINK+="ttyRelayCard", MODE="0666", OWNER="buildbot"
If there don’t have this code, please add it by manual. And then re-plugin the
relay card’s USB cable.
查看是否存在/etc/udev/rules.d/ACS.rules，如果不存在，则建立文件：touch ACS.rules，文件内容如上。
3. 查看权限：ls -l /dev/ttyRelayCard， 结果crw-rw---- 1 root dialout.
可以更改继电器权限：chmod a+rw /dev/ttyRelayCard. 这样坏处是，每次插拔继电器都要更改。
继电器的user是root, group是dialout。可以使当前用户从属于dialout用户组。查看user的用户组：groups user。更改user的附属用户组list: sudo usermod -G dialout,adm,...
4. python script
import serial
import sys, time
‘‘‘
ser = serial.Serial(
port=None, # number of device, numbering starts at
# zero. if everything fails, the user
# can specify a device string, note
# that this isn‘t portable anymore
# if no port is specified an unconfigured
# an closed serial port object is created
baudrate=9600, # baud rate
bytesize=EIGHTBITS, # number of databits
parity=PARITY_NONE, # enable parity checking
stopbits=STOPBITS_ONE, # number of stopbits
timeout=None, # set a timeout value, None for waiting forever
xonxoff=0, # enable software flow control
rtscts=0, # enable RTS/CTS flow control
interCharTimeout=None # Inter-character timeout, None to disable
)
‘‘‘
device = sys.argv[1] # /dev/ttyRelayCard
ser = serial.Serial(device, 19200, serial.EIGHTBITS, serial.PARITY_NONE, serial.STOPBITS_TWO, None)
W = 0.05
def get_version():
cmd = 90
print "get the relay software version"
ser.write(chr(cmd))
time.sleep(W)
a = ser.read(1)
print ord(a)
b = ser.read(1)
print ord(b)
time.sleep(1)
def set_relay_on(i):
‘‘‘ relay No is from 1 to 8‘‘‘
cmd = 100 + i
print "set relay %d on "%(i)
ser.write(chr(cmd))
time.sleep(W)
ser.write(chr(91)) # get relay states
a = ser.read(1)
print ord(a)
time.sleep(W)
def set_relay_off(i):
‘‘‘ relay No is from 1 to 8‘‘‘
cmd = 110 + i
print "set relay %d off"%(i)
ser.write(chr(cmd))
time.sleep(W)
ser.write(chr(91))
a = ser.read(1)
print ord(a)
time.sleep(W)
set_relay_off(1)
# set_relay_on(1)
附录
ZZR08 command Table
| Command | Action | ||
| Character | DEC | HEX | |
| 90 | 5A | Get software version - returns 2 bytes, the first being the module ID which is 8, followed by the software version |
|
| 91 | 5B | Get relay states -
sends a single byte back to the controller, bit high meaning the corresponding relay is powered |
|
| 92 | 5C | Set relay states -
the next single byte will set all relays states, All on = 255 (11111111) ,All off = 0 |
|
| d | 100 | 64 | All relays on |
| e | 101 | 65 | Turn relay 1 on |
| f | 102 | 66 | Turn relay 2 on |
| g | 103 | 67 | Turn relay 3 on |
| h | 104 | 68 | Turn relay 4 on |
| i | 105 | 69 | Turn relay 5 on |
| j | 106 | 6A | Turn relay 6 on |
| k | 107 | 6B | Turn relay 7 on |
| l | 108 | 6C | Turn relay 8 on |
| n | 110 | 6E | All relays off |
| o | 111 | 6F | Turn relay 1 off |
| p | 112 | 70 | Turn relay 2 off |
| q | 113 | 71 | Turn relay 3 off |
| r | 114 | 72 | Turn relay 4 off |
| s | 115 | 73 | Turn relay 5 off |
| t | 116 | 74 | Turn relay 6 off |
| u | 117 | 75 | Turn relay 7 off |
| v | 118 | 76 | Turn relay 8 off |
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原文地址：http://www.cnblogs.com/snow-backup/p/5013563.html
