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本文使用modbus slave软件模拟一个受控的modbus设备，此模拟设备提供如下功能：
1、线圈组1，8个线圈，起始地址为0，数量为8，软件设置如下(功能码1)，用于测试功能码5，一次写一个线圈：
2、线圈组2，8个线圈，起始地址为8，数量为8，软件设置如下(功能码1)，用于测试功能码15，一次写多个线圈。：
3、离散输入组，8个二进制离散输入，起始地址为0，数量为8，软件设置如下(功能码2)：
使用EPICS Modbus模块对以上modbus设备进行读写，过程如下：
使用makeBaseApp.pl构建IOC程序框架，并且在configure/RELEASE中指定base所在路径以及所需要的支持模块modbus路径。在程序的src路径下Makefile中指定要添加的数据块定义文件和库文件。
在程序的Db目录下，编写如下模板文件：
1） bo_bit.template：用于写modbus设备的单线圈
record(bo,"$(P)$(R)") {field(DTYP,"asynUInt32Digital")field(OUT,"@asynMask($(PORT) $(OFFSET) 0x1)")field(ZNAM,"$(ZNAM)")field(ONAM,"$(ONAM)")
}2）bi_bit.template：用于读modbus设备的线圈状态或者离散输入状态
record(bi,"$(P)$(R)") {field(DTYP,"asynUInt32Digital")field(INP,"@asynMask($(PORT) $(OFFSET) 0x1)")field(SCAN,"$(SCAN)")field(ZNAM,"$(ZNAM)")field(ONAM,"$(ONAM)")field(ZSV,"$(ZSV)")field(OSV,"$(OSV)")
}3）wfo_bit.template：用于一次写modbus设备的多个线圈
record(waveform,"$(P)$(R)") {field(DTYP,"asynInt32ArrayOut")field(INP,"@asyn($(PORT) $(OFFSET=0))MODBUS_DATA")field(FTVL,"ULONG")field(NELM,"$(NELM)")
}4） wfi_bit.template：用于读取modbus设备多个线圈状态或这多个离散输入状态。
record(waveform,"$(P)$(R)") {field(DTYP,"asynInt32ArrayIn")field(INP,"@asyn($(PORT) $(OFFSET=0))MODBUS_DATA")field(SCAN,"$(SCAN)")field(FTVL,"ULONG")field(NELM,"$(NELM)")
}将以上模板文件添加到相同路径下Makefile文件中：
...
DB += bo_bit.template
DB += bi_bit.template
DB += wfo_bit.template
DB += wfi_bit.template
...回到IOC顶层目录，执行make命令，编译这个IOC。
进入到启动目录iocBoot/iocmodbusbit中，编写记录实例化文件：
1）coil_bo_bits.substitutions：用于实例化8个bo记录，每个bo写modbus设备1个线圈。
file "../../db/bo_bit.template" { pattern
{P, R, PORT, OFFSET, ZNAM, ONAM}
{COUT:, CO0B, C0_Out_Bits, 0, Low, High}
{COUT:, CO1B, C0_Out_Bits, 1, Low, High}
{COUT:, CO2B, C0_Out_Bits, 2, Low, High}
{COUT:, CO3B, C0_Out_Bits, 3, Low, High}
{COUT:, CO4B, C0_Out_Bits, 4, Low, High}
{COUT:, CO5B, C0_Out_Bits, 5, Low, High}
{COUT:, CO6B, C0_Out_Bits, 6, Low, High}
{COUT:, CO7B, C0_Out_Bits, 7, Low, High}
}2）coil_bi_bits.substitutions：用于实例化16个bi记录，每个bi读取modbus设备1个线圈状态。
file "../../db/bi_bit.template" { pattern
{P, R, PORT, OFFSET, ZNAM, ONAM, ZSV, OSV, SCAN}
{CIN:, CI00B, C0_In_Bits, 0, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI01B, C0_In_Bits, 1, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI02B, C0_In_Bits, 2, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI03B, C0_In_Bits, 3, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI04B, C0_In_Bits, 4, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI05B, C0_In_Bits, 5, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI06B, C0_In_Bits, 6, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI07B, C0_In_Bits, 7, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI08B, C1_In_Bits, 0, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI09B, C1_In_Bits, 1, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI10B, C1_In_Bits, 2, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI11B, C1_In_Bits, 3, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI12B, C1_In_Bits, 4, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI13B, C1_In_Bits, 5, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI14B, C1_In_Bits, 6, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{CIN:, CI15B, C1_In_Bits, 7, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
}3）dis_bi_bits.substitutions：用于实例化8个bi记录，每个bi取modbus设备离散输入状态。
file "../../db/bi_bit.template" { pattern
{P, R, PORT, OFFSET, ZNAM, ONAM, ZSV, OSV, SCAN}
{DIN:, DI00B, D0_In_Bits, 0, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI01B, D0_In_Bits, 1, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI02B, D0_In_Bits, 2, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI03B, D0_In_Bits, 3, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI04B, D0_In_Bits, 4, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI05B, D0_In_Bits, 5, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI06B, D0_In_Bits, 6, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
{DIN:, DI07B, D0_In_Bits, 7, Low, High, NO_ALARM, MAJOR, "I/O Intr"}
}4）coil_wfo_bits.substitutions：实例化一个waveform记录，用于一次最多设置modbus设备8个线圈。
file "../../db/wfo_bit.template" { pattern
{P, R, PORT, OFFSET, NELM}
{COUT:, WFO, C0_Out_WF, 0, 8}
}5） dis_wfi_bits.substitutions：实例化一个waveform记录，用于读取modbus设备8个离散输入的状态。
file "../../db/wfi_bit.template" { pattern
{P, R, PORT, OFFSET, , NELM , SCAN}
{DIN:, WFI, D0_In_Bits, 8, 8, "I/O Intr"}
}编写启动脚本st.cmd：
#!../../bin/linux-x86_64/modbuspoll#- You may have to change modbuspoll to something else
#- everywhere it appears in this file< envPathscd "${TOP}"## Register all support components
dbLoadDatabase "dbd/modbuspoll.dbd"
modbuspoll_registerRecordDeviceDriver pdbbase# 连接modbus设备
drvAsynIPPortConfigure("mpoll","192.168.3.15:502",0,0,1)
# 使用modbus tcp类型
modbusInterposeConfig("mpoll", 0 ,2000,0)# 用于写线圈，起始地址0，每次写1个，一共写8次
drvModbusAsynConfigure("C0_Out_Bits", "mpoll", 0, 5, 0, 8, 0, 100, "mpoll")
# 用于写线圈，起始地址8，一次写8个线圈
drvModbusAsynConfigure("C0_Out_WF", "mpoll", 0, 15, 8, 8, 0, 100, "mpoll")# 用于读线圈，起始地址0，每次读取一个，一共读8次，轮询时间为500ms
drvModbusAsynConfigure("C0_In_Bits", "mpoll", 0, 1, 0, 8, 0, 500, "mpoll")
# 用于读线圈，起始地址8，每次读取一个，一共读8次，轮询时间为500ms
drvModbusAsynConfigure("C1_In_Bits", "mpoll", 0, 1, 8, 8, 0, 500, "mpoll")# 用于读取离散输入，起始地址0，每次读取一个，读取8次，轮询时间100ms
drvModbusAsynConfigure("D0_In_Bits", "mpoll", 0, 2, 0, 8, 0, 100, "mpoll")cd "${TOP}/iocBoot/${IOC}"
# 加载实例化记录
# 写线圈
dbLoadTemplate("coil_bo_bits.substitutions")
# 写线圈
dbLoadTemplate("coil_wfo_bits.substitutions")
# 读线圈
dbLoadTemplate("coil_bi_bits.substitutions")
# 读离散输入
dbLoadTemplate("dis_bi_bits.substitutions")
# 读离散输入
dbLoadTemplate("dis_wfi_bits.substitutions")iocInit
启动这个IOC：
[root@localhost iocmodbusbit]# ../../bin/linux-x86_64/modbuspoll st.cmd
#!../../bin/linux-x86_64/modbuspoll
...
# bit write
drvModbusAsynConfigure("C0_Out_Bits", "mpoll", 0, 5, 0, 8, 0, 100, "mpoll")
# bit array write
drvModbusAsynConfigure("C0_Out_WF", "mpoll", 0, 15, 8, 8, 0, 100, "mpoll")
# Coil bit Read
drvModbusAsynConfigure("C0_In_Bits", "mpoll", 0, 1, 0, 8, 0, 500, "mpoll")
drvModbusAsynConfigure("C1_In_Bits", "mpoll", 0, 1, 8, 8, 0, 500, "mpoll")
# Discrete bit Read
drvModbusAsynConfigure("D0_In_Bits", "mpoll", 0, 2, 0, 8, 0, 100, "mpoll")
cd "/usr/local/EPICS/program/modbuspoll/iocBoot/iocmodbusbit"
dbLoadTemplate("coil_bo_bits.substitutions")
dbLoadTemplate("coil_wfo_bits.substitutions")
dbLoadTemplate("coil_bi_bits.substitutions")
dbLoadTemplate("dis_bi_bits.substitutions")
dbLoadTemplate("dis_wfi_bits.substitutions")
iocInit
Starting iocInit
...
## Start any sequence programs
#seq sncxxx,"user=blctrl"
epics> dbl
COUT:CO0B
COUT:CO1B
COUT:CO2B
COUT:CO3B
COUT:CO4B
COUT:CO5B
COUT:CO6B
COUT:CO7B
COUT:WFO
DIN:WFI
CIN:CI00B
CIN:CI01B
CIN:CI02B
CIN:CI03B
CIN:CI04B
CIN:CI05B
CIN:CI06B
CIN:CI07B
CIN:CI08B
CIN:CI09B
CIN:CI10B
CIN:CI11B
CIN:CI12B
CIN:CI13B
CIN:CI14B
CIN:CI15B
DIN:DI00B
DIN:DI01B
DIN:DI02B
DIN:DI03B
DIN:DI04B
DIN:DI05B
DIN:DI06B
DIN:DI07B
1) COUT:CO0B~COUT:CO7B：bo记录，每个bo记录用于写一个线圈。
2）COUT:WF：waveform记录，用于一次写8个线圈。
3）DIN:WFI：waveform记录，用于读取8个离散输入。
4）CIN:CI00B~CIN:CI15B：bi记录，每个bi记录读取一个线圈状态。
5）DIN:DI00B~DIN:DI00B，bi记录，每个bi记录读取一个离散输入。
用css绘制控制界面，进行记录连接后，如下所示：
1）顶层窗口区域：Coil Out按钮写线圈，Coil In回读线圈状态
2）中间窗口区域：Coil Array Out可以一次最多写8个线圈，Coil In回读线圈状态。
3）底层窗口区域：用于读取离散输入，离散输入状态需要在modbus slave窗口中设置 ，Discrete Bit in 和Discrete Bit Array In都回读modbus slave窗口中设置的离散输入的状态。
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