Systran DAC128V

Current Author: Mark Rivers

Original Author: Jim Kolakowski

This file describes support for the Systran DAC128V, an 8 channel, 12-bit D/A converter. The following files are included in this support, which is available as a tar file:

• DAC128V.h	defines dac128V class
  dac128V.cc	communicates with hardware
  dac128VServer.cc	MPF server, interface between MPF and dac128V.cc
  devAoDAC128V.cc	EPICS device support code for ao (analog output record)
  devAoDAC128V.dbd	EPICS device support definition for ao (analog output record)
  dac128VREADME.html	This documentation file

Class DAC128V

This is a very simple class. This is the public interface of the DAC128V class:

class DAC128V
{
public:
    static DAC128V * init(
        const char *moduleName, const char *carrierName, const char *siteName);
    int setValue(int value, int channel);
    int getValue(int *value, int channel);

Brief description of these functions:

• init() is called from initDAC128V which is discussed below.
• setValue() sets the DAC value for a channel in raw units. It is called from dac128VServer.
• getValue() reads the current DAC value for a channel in raw units. It is called, for example, from the Ip300PID class.

This is an extremely simple server and IP driver. It simply writes an unsigned short into a register.

devAoDAC128V.dbd

This file contains the single line:

device(ao,VME_IO,devAoDAC128V,"dac128V")

EPICS Device Support

EPICS device support sends Int32Messages with the following info

• address - channel to write to (range 0-7)
• value - value to write (range 0-4095)

MPF server returns

• status=0 means success, anything else is failure

Standard input record type format is for ao records

field(SCAN,"1 second")

field(DTYP,"dac128V") (or whatever it might be called in your .dbd file)

field(INP,"#C{card} S{signal} @{servername}
card = The location of the server
signal = The output channel of the DAC128V. Channels 0 - 7 are valid
servername = Must match the modulename specified with initDAC128V

field(EGUF,"{FULL VALUE}") This is set by a jumper on the IP module. The jumper affects groups of 4 channels. The choices are -10V, -5V, 0V, +5V and +10V.

field(EGUL,"{LOW VALUE}") This is set by a jumper on the IP module. The jumper affects groups of 4 channels. The choices are -10V, -5V, 0V, +5V and +10V.

field(LINR,"LINEAR") Optional

NOTE: The DAC128V powers up with each output set to midrange, i.e. 2048. This will only be 0V if the module is jumpered for symmetric, bipolar ouput. BEWARE!!!!

Server Configuration

pDAC128V = initDAC128V("modulename", "carrier", "site", "queueSize")

where

• modulename - must match the INP parm field in records
• carrier - The ip carrier name
• site - carrier IP site
• queueSize - message queue size. Make this the maximum number of records attached to this device.
• pDAC128V - pointer to a DAC128V object. This pointer is needed, for example, in initIp330PID.

Release Notes

• May 17, 2000. Added getValue() method, needed by Ip300PID class.
• Sept. 27, 2002.  Fixed bug in device support initialization.  It was returning 0, rather than 2 (MPF_NoConvert).  This could cause the initial value of the .VAL field to be corrupted.