NB: This manual refers to a very old version of EPICS, see the EPICS Wiki for updated record reference documentation.

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EPICS Record Reference Manual

Chapter 37: Timer

1. Introduction


The timer record is provided as a means for configuring timing outputs. These records will drive an output that may be used to latch data into analog inputs or waveform digitizers. The fields for the timer record fall into the following categories:

scan parameters

setup parameters

write and convert parameters

operator display parameters

event generation parameters

run-time parameters

2. Scan Parameters


The timer record has the standard fields for specifying under what circumstances it will be processed. In addition, the VAL field is provided in the timer record to force record processing when written to. The other fields are listed in Scan Fields, Chapter 2, 2. In addition, Scanning Specification, Chapter 1, 1, explains how these fields are used. Note that I/O event scanning is only supported for those card types that interrupt.
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
VALValue Field SHORTNo0YesYesYesYes

3. Setup Parameters


The timer record has fields needed to initialize a motor. The trigger source (TRSC) field is usually configured to come in from an external signal. This is configured in the record by setting TSRC to external, the only other choice being internal. The pre-trigger state field (PSRC) is the state of the timing channel when it is not fired. The timing channel usually goes high when the timing pulse is present. In such a case the pre-trigger state is low.
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
TSRCClock Source RECCHOICEYes0YesYesNoNo
PTST Pre-Trigger State RECCHOICEYes0YesYesNoYes

4. Write and Convert Parameters


The delays and outputs are specified in the time units (TIMU), which has four choices based on seconds: Milliseconds, Microseconds, Nanoseconds, and Picoseconds.

There are delays and pulse widths for five timing pulses per channel. The pulse width for each should be specified in the OPW1-OPW5 fields, in the units chosen in the TIMU field. The delay width for each trigger is specified in the DUT1-DUT5 fields. The delay width is the time in between pulses. These fields are converted to seconds by the run-time code before being used.

The value of the trigger delay field (TRDL) fetched from the trigger origin (TORG) field is added to the delay for each of these five signals. The TORG and TRDL work like the desired output parameters of other output records. TORG can be a channel access or database link, or a constant. If TORG is a constant, TRDL is initialized to the constant value and can be changed at run-time via dbPuts. Using the TORG field one can set up timing chains which are relative to other timing signals. See Address Specification, Chapter 1, 2, for information on how to specify database links.

The desired output is sent to the address contained in the output link (OUT). The DTYP field must contain the name of a valid device support module. The user can see a list of the device support modules currently supported at the user's local site by using the dbst utility (R3.13).
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
TORGTrigger Delay Origin (input link)INLINKYes0NoNoN/ANo
TRDLTrigger Delay FLOATNo0YesYesNoNo
TIMU Timer UnitsRECCHOICEYes0YesYesNoNo
DTYPDevice TypeDEVCHOICEYes0YesNoNoNo
OUT Output Link OUTLINKYes0NoNoN/ANo
DUT1Delay Width for trigger 1FLOATYes0YesYesNoYes
OPW1Pulse width for Trigger 1FLOATYes0YesYesNoYes
DUT2Delay Width for Trigger 2FLOATYes0YesYesNoYes
OPW2Pulse Width for Trigger 2FLOATYes0YesYesNoYes
DUT3Delay Width for Trigger 3FLOATYes0YesYesNoYes
OPW3Pulse Width for Trigger 3FLOATYes0YesYesNoYes
DUT4Delay Width for Trigger 4FLOATYes0YesYesNoYes
OPW4Pulse Width for Trigger 4FLOATYes0YesYesNoYes
DUT5Delay Width for Trigger 5FLOATYes0YesYesNoYes
OPW5Pulse Width for Trigger 5FLOATYes0YesYesNoYes

5. Operator Display Parameters


The PDLY field displays the delay from source to input, which is the time is takes for the timing signal to get from its output to the trigger. It is not used by the run-time code, but characterizes the timing signals for the operator's knowledge.

See Chapter 2, Fields Common to All Record Types, for more on the record name (NAME) and description (DESC) fields.
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
PDLYDelay Source to InputFLOATYes0YesYesNoNo
NAMERecord NameSTRING [29]Yes0YesNoNoNo
DESCDescriptionSTRING [29]YesNullYesYesNoNo

6. Alarm Parameters


The timer record has the alarm parameters common to all record types. Alarm Fields, Chapter 2, 3, lists other fields related to a alarms that are common to all record types.

7. Event Generation Parameters


The timing event (TEVT) field is used to generate internal events for processing records on an event. It should be an integer representing an event number.
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
TEVTEvent Number To Be Posted On Trigger. SHORTYes0YesYesNoYes

8. Run-time Parameters


These parameters are used by the run-time code for processing the timing channel. They are not configured using a configuration tool. They represent the current state of the timing channel.

The T1DL-T5DL and T1WD-T5WD fields are where the record stores the user-configured delay widths and pulse widths for the five triggers (DUT1-DUT5 and OPW1-OPW5) after it has converted them to seconds.

The T1TD-T5TD and T1LD-T5LD fields hold the trailing and leading trigger delays for each trigger. These fields are calculated by the record as follows:

TnLD = DUTn + TRDL

TnTD = TnLD + OPWn

--where n represents the trigger number.
FieldSummaryTypeDCTInitialAccessModifyRec Proc MonitorPP
T1DLDelay Width for Trigger 1DOUBLENo0YesYesNoNo
T1WDPulse Width for Trigger 1DOUBLENo0YesYesYesNo
T2DLDelay Width for Trigger 2DOUBLENo0YesYesNoNo
T2WDPulse Width for Trigger 2DOUBLENo0YesYesNoNo
T3DLDelay Width for Trigger 3DOUBLENo0YesYesNoNo
T3WDPulse Width for Trigger 3DOUBLENo0YesYesNoNo
T4DLDelay Width or Trigger 4DOUBLENo0YesYesNoNo
T4WDPulse Width for Trigger 4DOUBLENo0YesYesNoNo
T5DLDelay width for Trigger 5DOUBLENo0YesYesNoNo
T5WDPulse Width for Trigger 5DOUBLENo0YesYesNoNo
T1TDTrigger 1 Trailing DelayFLOATNo0YesYesYesNo
T1LDTrigger 1 Leading DelayFLOATNo0YesYesYesNo
T2TDTrigger 2 Trailing Delay FLOATNo0YesYesNoNo
T2LDTrigger 2 Leading DelayFLOATNo0YesYesNoNo
T3TDTrigger 3 Trailing DelayFLOATNo0YesYesNoNo
T3LDTrigger 3 Leading DelayFLOATNo0YesYesNoNo
T4TDTrigger 4 Trailing DelayFLOATNo0YesYesNoNo
T4LDTrigger 4 Leading DelayFLOATNo0YesYesNoNo
T5TDTrigger 5 Trailing DelayFLOATNo0YesYesNoNo
T5LDTrigger 5 Leading DelayFLOATNo0YesYesNoNo
TDISTiming Pulse DisableSHORTNo0YesYesNoYes
MAINMaintain on Reboot GBLCHOICEYes1YesYesNoYes
RDT1Reboot Delay of 1 FLOATNo0YesYesNoNo
RDW1Reboot Width of 1 FLOATNo0YesYesNoNo

1. - Introduction
2. - Scan Parameters
3. - Setup Parameters
4. - Write and Convert Parameters
5. - Operator Display Parameters
6. - Alarm Parameters
7. - Event Generation Parameters
8. - Run-time Parameters

EPICS Record Reference Manual - 19 MAY 1998
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