继电器Relay：ZZR08

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