EPICS IOC On Board

D-TACQ Intelligent digitizers work with EPICS.
Each card is a networked Linux system and the EPICS IOC has been ported to run onboard, this means that D-TACQ digitizers need only an Ethernet connection in order to participate in an EPICS control system, publishing data using standard EPICS Channel Access. Works with off-the-shelf linux-arm architecture in EPICS BASE 3-14-11.

Two device support layers are provided:

• dsSysfs A Device Support layer dsSysfs makes linking device files to EPICS records easy. "No Drivers Required". Any system file with a scalar content (eg /proc/uptime) may be hooked. This works really well on ACQ196, since virtual file "knobs" are provided for most parameters.
• lxb Linux Binary - provides highly efficient support for Digital Inputs. We provide a standard Linux device driver with a blocking read() call, returing on Change Of State (COS). The device support hooks each state bit to a BI record in the EPICS db. This model could easily be applied to any DI device - including the ACQ196 DIO32 port on the RTM and the 128bit third party "Adlink" cp7542 isolated DIO module.

Typical use case:

Continuous capture with low rate trend data provided by AI records. Capture stops on a trip condition, then full rate pre/post data is presented in the Waveform record.
Combined Process Controller and Transient Digitizer.

Standard record support includes:

• Analog Input AI trend data - per channel rolling average during full rate capture to memory
• Waveform records update analog input data on completion of transient capture.
• Simple start/stop controls, acquisition state monitoring.
• System health monitoring - card temperature and heartbeat.
• Analog Output AO records where AO channels are fitted. (eg RTM-AO16).
• BI/BO records to interface to DIO32 (32 bit bit-programmable DIO port).
• BI records to monitor system clocks and triggers.
• Easy to add simple sequences - eg analog ratio crossing triggers digital output alarm.
• Support for EPICS sequencer (snc/seq) allowing arbitrarily complex automation sequences to be developed in a high-level notation.
• Future options - MBBI records to access 32 bit DIO port, local Serial port [UART] access.
• Easy to add additional ports: octal serial UART, using build in system slot functionality to host CPCI peripheral cards and/or PMC modules
• Support for D-TACQ AO32CPCI - 32 AO records, AWG, 64 bit BO,
• Support for ADLINK CP7452 - 128 BI, 128 BO.

Resources:

• ACQ2XX EPICS User Guide (pdf)
• IOC source, dsSysfs, lxb device support source/doc/binary
• Example: minimum record set (status, temp, no IO) epics-min-ioc.tar
• Example: use CALC records to compute a channel difference threshold trip
• Example: Combined Process Controller and Transient Digitizer / MEDM setup / howto

Embedded EPICS for control, MDSplus for data - get the best of both worlds