/modbus-example

Primary LanguageHTML

EPICS Modbus example

Examples

st_func_code_1.cmd

For DO (Server) / DI (EPICS BI), DATA_LENGTH = START_ADDR + No of Coils. For example, Server's Start addr is 0, and has 20 Coils, then EPICS IOC DATA_LENGTH is 20.

  • Case 1 : DATA_LENGTH = 20, and the server also has 20 coils and the number of PVs is 21. We see the PVs are updating according to that server value changing.
drvModbusAsyn::readPoller port A0_In_Bits invalid offset 20, max=20
  • Case 2 : DATA_LENGTH = 50, and server has only 20 coils, and the number of PVs is 20. PV values doesn't change.
drvModbusAsyn::doModbusIO port A0_In_Bits Modbus exception=2

  • Case 3 : DATA_LENGTH = 20, and server has 20 coils, and the number of PV is 17. We skip offset 3,10,16, and 20. All defined PVs are updating properly.

  • Case 4 : DATA_LENGTH = 10, and server has 20 coils and the number of PVs is 10 with 0 - 9 offset. All PV values are updating.

  • Case 5 : DATA_LENGTH = 10, and server has 20 coils and the number of PVs is 10 with 0,2,4, ..., 18 offsets. PV values with offset lower than 10 are updating. However, PVs with offset >=10 doesn't change.

drvModbusAsyn::readPoller port A0_In_Bits invalid offset 10, max=10
  • Case 6 : DATA_LENGTH=20, and server has 20 coils, and 20 PVs. But server has UNIT_ID=2, EPICS has UNIT_ID=1.
devAsynUInt32Digital::initCommon connectDevice failed asynManager:connectDevice port A0_In_Bits not found

st_func_code_5.cmd

  • case 1 : DATA_LENGTH=20, and server has 20 coils, and 10 PVs. EPICS can write 10 PV values sequentially with caput_5.bash.
epicsEnvSet("MOD_NAME", "A0_Out_Bits" )
epicsEnvSet("FUNC_CODE", 5)
epicsEnvSet("ELEMENT",  20)

simulator

ln -s /usr/bin/pluma ~/bin/notepad.exe