DISPLAYING AN EPICS WAVEFORM DATA AS AN IMAGE IN PYTHON/TKINTER

Scripting languages such as Python and SAD together with Tk widgets are successfully used in the KEKB con-trol system. These tools enhances flexibility and usability of the system. Its performance satisfies most of require-ment in the system. However, some application, such as an image display on the operator screen, may hits their perfor-mance limit. This performance limits can be easily over-come combining a Tk widget and an EPICS CA callback in the C language level rather than interpreter level. Use of this approach enable us to update an image on a X window screen at 20 frame per second or higher through EPICS channel access. EPICS AND SCRIPTING LANGUAGES EPICS is a software toolkit to construct wide variety of control system based on network distributed architec-ture [1]. EPICS provides generic software for building and running operator user interfaces. These software, called EPICS CA clients, are configurable through a configura-tion file and fulfill most of needs in a control system. However, some applications requires the functionality beyond the ability these tools can provide. Then we need to develop an application to satisfy this requirement. Script-ing languages, such as Tcl/Tk, Perl, Mathematica, PV-wave, Python and SAD, are widely used in the EPICS collaboration[2]. These languages are used for prototyping these applications, however, in some cases, the applications were written in these scripting languages. Python, Tcl/Tk /BLT widget and EPICS CA Python is an object oriented scripting language devel-oped by G. von Rossoum. One of its rich extension mod-ules is Tkinter.py which enable us to access Tk widget from Python programs. Tk toolkit includes a widget for present-ing photo image on display. An image on this photo image widget can be dynamically modified supplying pixel data of new image. EPICS channel access interface for Python was devel-oped by author and is used in the KEKB control system[3] and will be used in J-PARC project[4]. When the EPICS CA module receives data from CA, binary channel data is converted to Python object in the callback routine [Fig. 1]. BLT[5] is an extension library Tcl/Tk widget. Among the functionality provided by BLT, a graph widget and