e3-ecmc_plugin_pva

ESS Site-specific EPICS module : ecmc_plugin_pva

A shared library utility functions loadable into ecmc.

PvAccess

Implements functions for accessing pv:s over pvAccess from ecmc plc:s.

Registering and writing pvs:

Registration and writes are implementad as async commands in order to minimize blocking time of ecmc realtime thread. Even though the "pvaClient::issue*" commands are non blocking they were idetified to consume to much time. Therefore both registration and writing commands are handled async by a low prio worker thread. The pv_busy() command will return high as long as the worker thread is procssing and low when done (see examples in "iocsh" dir).

Reading values:

A monitor is continiously updating the current value of the pv and making it accessible to read by "pv_get()" command in an ecmc-plc.

PLC-functions:

• handle = pv_reg_async( pvName, provider ) : Exe. async cmd to register PV. Returns handle to PV-object or error (if < 0). Provider needs to be set to either "pva" or "ca" (ca to be able to access pv:s in EPICS 3.* IOC:s).
• error = pv_put_async( handle, value ) : Exe async pv put command. Retruns error-code.
• value = pv_get( handle ): Get pv value from last monitor update.
• busy = pv_busy( handle ) : Return if PV-object is busy (busy if a pv_put_asyn() or a pv_reg_asyn() async command is executing).
• error = pv_err( handle ) : Returns error code of PV-objects last command (error > 0).
• connected = pv_connected() : Return if pv is connected.

Config options

MAX_PV_COUNT= : Sets the maximum number of pv:s to register. These pv objects will be allocated when module is loaded (before realtime). This setting defaults to 8.

Record support

The functions currently only support scalar values. Value field of following record types have been tested:

• AI
• AO
• BI (enum_t: return index of enum value)
• BO (enum_t: sets index of enum value)

Example

The example in the "iocsh" dir shows how to use the pva functions. The example demonstartes how a ecmc plc (in an ecmc ioc) can connect to an external ioc. The ecmc plc registers, writes and reads values from the folowing records:

• IOC_DUMMY:AI
• IOC_DUMMY:AO
• IOC_DUMMY:BI
• IOC_DUMMY:BO

Start the "ecmc-ioc" (from iocsh dir):

$ iocsh.bash ecmc_ioc.script

Start the "external-ioc" (from iocsh dir):

$ iocsh.bash external_ioc.script

The "ecmc-ioc" will now connect to, read and write pvs in the "external-ioc" and generates some printouts:

Get AI from PV: 117.00000
Put AO to PV  : 118.00000
pv_put_asyn AO exe time [ns] : 10240.00000
Busy after pv_put_asyn():    1.00000
Get BI from PV:   1.00000
Put BO to PV  :   0.00000
Busy after pv_put_asyn():    1.00000, err:    0.00000
pv_get AI exe time [ns] : 4096.00000
Get AI from PV: 118.00000
Put AO to PV  : 119.00000
pv_put_asyn AO exe time [ns] : 10240.00000
Busy after pv_put_asyn():    1.00000
Get BI from PV:   0.00000
Put BO to PV  :   1.00000

EPICS utils:

• started = ioc_get_started() : ecmc IOC up and running
• state = ioc_get_state() : ecmc IOC state (hook)

Setup

$ make install

Plugin Info

Plugin info: 
  Index                = 0
  Name                 = ecmcPlugin_Utils
  Description          = Utility plugin for use with ecmc. Funcs: pvAccess, ioc status.
  Option description   = MAX_PV_COUNT=<count> : Set max number of pvs to connect to (defaults to 8).
  Filename             = /epics/base-7.0.4/require/3.3.0/siteMods/ecmc_plugin_pva/master/lib/linux-arm/libecmc_plugin_pva.so
  Config string        = MAX_PV_COUNT=5
  Version              = 2
  Interface version    = 65536 (ecmc = 65536)
     max plc funcs     = 64
     max plc func args = 10
     max plc consts    = 64
  Construct func       = @0xb5023b4c
  Enter realtime func  = @0xb5023a58
  Exit realtime func   = @0xb5023a60
  Realtime func        = @0xb5023a50
  Destruct func        = @0xb5023a68
  dlhandle             = @0x1844100
  Plc functions:
    funcs[00]:
      Name       = "pv_reg_asyn();"
      Desc       = handle = pv_reg_asyn(<pv name>, <provider name pva/ca>) : register new pv.
      func       = @0x18581d8
    funcs[01]:
      Name       = "pv_put_asyn(arg0, arg1);"
      Desc       = error = pv_put_asyn(<handle>, <value>) : Execute async pv_put cmd.
      Arg count  = 2
      func       = @0xb5023a8c
    funcs[02]:
      Name       = "pv_get(arg0);"
      Desc       = value = pv_get(<handle>) : Get value of registered pv (updated by monitor).
      Arg count  = 1
      func       = @0xb5023aac
    funcs[03]:
      Name       = "pv_busy(arg0);"
      Desc       = busy = pv_busy(<handle>) : Get status of last async command (pv_reg_asyn(), pv_put_asyn()).
      Arg count  = 1
      func       = @0xb5023ab8
    funcs[04]:
      Name       = "pv_err(arg0);"
      Desc       = error = pv_err(<handle>) : Get error code.
      Arg count  = 1
      func       = @0xb5023af0
    funcs[05]:
      Name       = "pv_connected(arg0);"
      Desc       = connected = pv_connected(<handle>) : Get pv connected.
      Arg count  = 1
      func       = @0xb5023ad4
    funcs[06]:
      Name       = "ioc_get_state();"
      Desc       = state = ioc_get_state() : Get ecmc epics ioc state.
      Arg count  = 0
      func       = @0xb5023b38
    funcs[07]:
      Name       = "ioc_get_started();"
      Desc       = started = ioc_get_started() : Get ecmc epics ioc started.
      Arg count  = 0
      func       = @0xb5023b0c
  Plc constants: