RRM 3-14 Multi-Bit Binary Input

EPICS Record Reference Manual

mbbi -- Multi-Bit Binary Input

The normal use for the multi-bit binary input record is to read contiguous, multiple bit inputs from hardware. The binary value represents a state from a range of up to 16 states. The multi-bit input record interfaces with devices that use more than one bit.

Most device support modules obtain values from hardware and place the value in RVAL. For these device support modules record processing uses RVAL to determine the current state (VAL is given a value between 0 and 15). Device support modules may optionally read a value directly into VAL.

Soft device modules are provided to obtain input via database or channel access links or via dbPutField or dbPutLink requests. Two soft device support modules are provided: Soft Channel allows VAL to be an arbitrary unsigned short integer. Raw Soft Channel reads the value into RVAL just like normal device support modules.

Parameter Fields

The multi-bit binary input fields fall into the following categories:

• scan parameters
• read and convert parameters
• operator display parameters
• alarm parameters
• run-time and simulation mode parameters

Scan parameters

The multi-bit binary input record has the standard fields for specifying under what circumstances it will be processed. These fields are listed in Scan Fields. In addition, Scanning Specification explains how these fields are used. Note that I/O event scanning is only supported for those card types that interrupt.

Read and Convert Parameters

The device support routines obtain the record's input from the device or link specified in the INP field. For records that obtain their input from devices, the INP field must contain the address of the I/O card, and the DTYP field must specify the proper device support module. Be aware that the address format differs according to the I/O bus used. See Address Specification for information on the format of hardware addresses. You can see a list of the device support modules currently supported at the user's local site by using the dbst utility in R3.13.

Two soft device support modules can be specified in DTYP--Soft Channel and Raw Soft Channel. Raw Soft Channel reads the value into RVAL, upon which the normal conversion process is undergone. Soft Channel reads any unsigned integer directly into VAL. For a soft mbbi record, the INP field can be a constant, a database, or a channel access link. If INP is a constant, then the VAL is initialized to the constant value but can be changed at run-time via dbPutField or dbPutLink. See Address Specification for information on the format of database addresses.

MASK is used by the raw soft channel read routine, and by typical device support read routines, to select only the desired bits when reading the hardware register. It is initialized to ((1 << NOBT) - 1) by record initialization. The user can configure the NOBT field, but the device support routines may set it, in which case the value given to it by the user is simply overridden. The device support routines may also override MASK or shift it left by SHFT bits. If MASK is non-zero, only the bits specified by MASK will appear in RVAL.

Unless the device support routine specifies no conversion, RVAL is used to determine VAL as follows:

1. RVAL is assigned to a temporary variable -- rval = RVAL
2. rval is shifted right SHFT number of bits.
3. A match is sought between rval and one of the state value fields, ZRVL-FFVL.

Each of the fields, ZRVL-FFVL, represents one of the possible sixteen states (not all sixteen have to be used).

Alternatively, the input value can be read as a string, in which case, a match is sought with one of the strings specified in the ZRST-FFST fields. Then RVAL is set equal to the corresponding value for that string, and the conversion process occurs.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
VAL	Value Field	ENUM	No	0	Yes	Yes	Yes	Yes
INP	Input Link	INLINK	Yes	0	Yes	Yes	No	No
MASK	Mask	ULONG	No	0	Yes	No	No	No
NOBT	Number of Bits	SHORT	Yes	0	Yes	No	No	No
RVAL	Raw Data Value	ULONG	No	0	Yes	Yes	Yes	Yes
SHFT	Shift	USHORT	No	0	Yes	No	No	No
ZRVL	Zero Value	ULONG	Yes	0	Yes	Yes	No	Yes
ONVL	One value	ULONG	Yes	0	Yes	Yes	No	Yes
TWVL	Two Value	ULONG	Yes	0	Yes	Yes	No	Yes
THVL	Three Value	ULONG	Yes	0	Yes	Yes	No	Yes
FRVL	Four Value	ULONG	Yes	0	Yes	Yes	No	Yes
FVVL	Five Value	ULONG	Yes	0	Yes	Yes	No	Yes
SXVL	Six Value	ULONG	Yes	0	Yes	Yes	No	Yes
SVVL	Seven Value	ULONG	Yes	0	Yes	Yes	No	Yes
EIVL	Eight value	ULONG	Yes	0	Yes	Yes	No	Yes
NIVL	Nine Value	ULONG	Yes	0	Yes	Yes	No	Yes
TEVL	Ten Value	ULONG	Yes	0	Yes	Yes	No	Yes
ELVL	Eleven Value	ULONG	Yes	0	Yes	Yes	No	Yes
TVVL	Twelve Value	ULONG	Yes	0	Yes	Yes	No	Yes
TTVL	Thirteen Value	ULONG	Yes	0	Yes	Yes	No	Yes
FTVL	Fourteen Value	ULONG	Yes	0	Yes	Yes	No	Yes
FFVL	Fifteen Value	ULONG	Yes	0	Yes	Yes	No	Yes
ZRST	Zero String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
ONST	One String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
TWST	Two String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
THST	Three String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
FRST	Four String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
FVST	Five String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
SXST	Six String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
SVST	Seven String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
EIST	Eight String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
NIST	Nine String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
TEST	Ten String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
ELST	Eleven String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
TVST	Twelve String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
TTST	Thirteen String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
FTST	Fourteen String	STRING [16]	Yes	Null	Yes	Yes	No	Yes
FFST	Fifteen String	STRING [16]	Yes	Null	Yes	Yes	No	Yes

Operator Display Parameters

These parameters are used to present meaningful data to the operator. They display the value and other parameters of the mbbi record either textually or graphically. The ZRST-FFST fields contain strings describing one of the possible states of the record. The get_enum_str and get_enum_strs record routines retrieve these strings for the operator. Get_enum_str gets the string corresponding to the value set in VAL, and get_enum_strs retrieves all the strings.

See Fields Common to All Record Types for more on the record name (NAME) and description (DESC) fields.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
ZRST,...,FFST	Zero String, One String, ...	STRING [16]	Yes	Null	Yes	Yes	No	Yes
NAME	Record Name	STRING [29]	Yes	0	Yes	No	No
DESC	Description	STRING [29]	Yes	Null	Yes	Yes	No	No

Alarm Parameters

The possible alarm conditions for multi-bit binary inputs are the SCAN, READ, and state alarms. The state alarms are configured in the below severity fields. These fields have the usual possible values for severity fields: NO_ALARM, MINOR, and MAJOR.

The unknown state severity (UNSV) field, if set to MINOR or MAJOR, triggers an alarm when the record support routine cannot find a matching value in the state value fields for rval.

The change of state severity (COSV) field triggers an alarm when any change of state occurs, if set to MAJOR or MINOR.

The other fields, when set to MAJOR or MINOR, trigger an alarm when VAL equals the corresponding state. See the See Alarm Specification for a complete explanation of discrete alarms and these fields. Alarm Fields lists other fields related to a alarms that are common to all record types.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
UNSV	Unknown State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
COSV	Change of State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
ZRSV	0 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
ONSV	1 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
TWSV	2 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
THSV	3 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
FRSV	4 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
FVSV	5 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
SXSV	6 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
SVSV	7 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
EISV	8 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
NISV	9 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
TESV	10 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
ELSV	11 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
TVSV	12 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
TTSV	13 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
FTSV	14 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes
FFSV	15 State Severity	GBLCHOICE	Yes	0	Yes	Yes	No	Yes

Run-time Parameters

These parameters are used by the run-time code for processing the multi-bit binary input.

ORAW is used by record processing to hold the prior RVAL for use in determining when to post a monitor event for the RVAL field.

The LALM field implements the change of state alarm severity by holding the value of VAL when the previous change of state alarm was issued.

MLST holds the value when the last monitor for value change was triggered.

SDEF is used by record support to save time if no states are defined.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
ORAW	Old Raw Data	ULONG	No	0	Yes	No	No	No
LALM	Last Alarmed	USHORT	No	0	Yes	No	No	No
MLST	Monitor Last	USHORT	No	0	Yes	No	No	No
SDEF	States Defined?	SHORT	No	0	Yes	No	No	No

Simulation Mode Parameters

The following fields are used to operate the mbbi record in the simulation mode. See Fields Common to Many Record Types for more information on these fields.

Field	Summary	Type	DCT	Initial	Access	Modify	Rec Proc Monitor	PP
SIOL	Simulation Value Location	INLINK	Yes	0	Yes	Yes	No	No
SVAL	Simulation Value	DOUBLE	No	0	Yes	Yes	No	No
SIML	Simulation Mode Location	INLINK	Yes	0	Yes	Yes	No	No
SIMM	Simulation Mode	GBLCHOICE	No	0	Yes	Yes	No	No
SIMS	Simulation Mode Alarm Severity	GBLCHOICE	Yes	0	Yes	Yes	No	No

Record Support

Record Support Routines

init_record

This routine initializes SIMM with the value of SIML if SIML type is CONSTANT link or creates a channel access link if SIML type is PV_LINK. SVAL is likewise initialized if SIOL is CONSTANT or PV_LINK.

This routine next checks to see that device support is available and a device support read routine is defined. If either does not exist, an error message is issued and processing is terminated.

Clears MASK and then sets the NOBT low order bits.

If device support includes init_record, it is called.

init_common is then called to determine if any states are defined. If states are defined, SDEF is set to TRUE.

process

See next section.

special

Calls init_common to compute SDEF when any of the fields ZRVL, ... FFVL change value.

get_value

Fills in the values of struct valueDes so that they refer to VAL.

get_enum_str

Retrieves ASCII string corresponding to VAL.

get_enum_strs

Retrieves ASCII strings for ZRST,...FFST.

put_enum_str

Checks if string matches ZRST,...FFST and if it does, sets VAL.

Record Processing

Routine process implements the following algorithm:

1. Check to see that the appropriate device support module exists. If it doesn't, an error message is issued and processing is terminated with the PACT field still set to TRUE. This ensures that processes will no longer be called for this record. Thus error storms will not occur.
2. readValue is called. See Input Records for more information.
3. If PACT has been changed to TRUE, the device support read routine has started but has not completed reading a new input value. In this case, the processing routine merely returns, leaving PACT TRUE.
4. Convert:
   • status=read_mbbi
   • PACT = TRUE
   • TIME = tsLocalTime
   • If status is 0, then determine VAL
     • Set rval = RVAL
     • Shift rval right SHFT bits
   • If at least one state value is defined
     • Set UDF to TRUE
   • If RVAL is ZRVL,...,FFVL then set
     • VAL equals index of state
     • UDF set to FALSE
   • Else set VAL = undefined
     • Else set VAL = RVAL
   • Set UDF to FALSE
     • If status is 1, return(0)
   • If status is 2, set status = 0
5. Check alarms. This routine checks to see if the new VAL causes the alarm status and severity to change. If so, NSEV, NSTA and LALM are set.
6. Check to see if monitors should be invoked.
   • Alarm monitors are invoked if the alarm status or severity has changed.
   • Archive and value change monitors are invoked if MLST is not equal to VAL.
   • Monitors for RVAL are checked whenever other monitors are invoked.
   • NSEV and NSTA are reset to 0.
7. Scan forward link if necessary, set PACT FALSE, and return.

Device Support

Fields Of Interest To Device Support

Each input record must have an associated set of device support routines.

The primary responsibility of the device support routines is to obtain a new raw input value whenever read_mbbi is called. The device support routines are primarily interested in the following fields:

Name	Summary	Description
PACT	Processing Active	See Fields Common to All Record Types for an explanation of these fields.
DPVT	Device Private
UDF	VAL Undefined
NSEV	New Alarm Severity
NSTA	New Alarm Status
NOBT	Number of Bits	Number of hardware bits accessed. They must be consecutive.
VAL	Value Field	This field is set by the device support routines if they don't want record support to set it.
INP	Input Link	This field is used by the device support routines to locate its input.
RVAL	Raw Data Value	It is the responsibility of the device support routine to give this field a value.
MASK	Mask	This is a mask used to read the hardware. Record support sets the low order NOBT bits. The device support routine can shift the bits. The device support routine should perform the shift in init_record.
SHFT	Shift	This can be set by the device support module at init_record time.

Device Support Routines

Device support consists of the following routines:

report

report(FILE fp, paddr)

Not currently used.

init

init()

This routine is called once during IOC initialization.

init_record

init_record(precord)

This routine is optional. If provided, it is called by the record support init_record routine. If it uses MASK, it should shift it as necessary and also give SHFT a value.

get_ioint_info

get_ioint_info(int cmd,struct dbCommon *precord,IOSCANPVT *ppvt)

This routine is called by the ioEventScan system each time the record is added or deleted from an I/O event scan list. cmd has the value (0,1) if the record is being (added to, deleted from) an I/O event list. It must be provided for any device type that can use the I/O Event scanner.

read_mbbi

read_mbbi(precord)

This routine must provide a new input value. It returns the following values:

• 0: Success. A new raw value is placed in RVAL. The record support module determines VAL from RVAL, SHFT, and ZEVL ... FFVL.
• 2: Success, but don't modify VAL.
• Other: Error.

Device Support For Soft Records

Two soft device support modules Soft Channel and Raw Soft Channel are provided for multi-bit binary input records not related to actual hardware devices. The INP link type must be either CONSTANT, DB_LINK, or CA_LINK.

Soft Channel

read_mbbi always returns a value of 2, which means that no conversion is performed.

If the INP link type is constant, then the constant value is stored into VAL by init_record, and UDF is set to FALSE. VAL can be changed via dbPut requests. If the INP link type is PV_LINK, then dbCaAddInlink is called by init_record.

read_mbbi calls recGblGetLinkValue to read the current value of VAL. See Soft Input.

If the return status of recGblGetLinkValue is zero, then read_mbbi sets UDF to FALSE. The status of recGblGetLinkValue is returned.

Raw Soft Channel

This module is like the previous except that values are read into RVAL, VAL is computed from RVAL, and read_mbbi returns a value of 0. Thus the record processing routine will determine VAL in the normal way.

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EPICS Record Reference Manual - 19 MAY 1998