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<== Date ==>		<== Thread ==>

Subject:	Re: Naming conventions for devices and Epics records
From:	Ralph Lange <[email protected]>
To:	Lecorche Eric <[email protected]>
Cc:	EPICS Tech Talk <[email protected]>
Date:	Fri, 17 Nov 2006 17:04:49 +0100

Well - that was easy. Here's the BESSY part about signal naming. We just started to enforce rules on signal names after some years of experience with everything after the colon being free-style. So - no experience with these signal naming rules. Yet.

Ralph

Ralph Lange wrote:

You can see the BESSY Device naming conventions in the "Concepts" part on

http://www-csr.bessy.de/control/Docs/

(which should be visible from the outside - the APS page Pete was mentioning is not)

We also have a convention for signal names (everything after the first colon) - but that is only available from within BESSY. Maybe I can save and mail it to you.

Ralph

Title: SignalNamingConv < Controls < TWiki

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r11 - 10 Nov 2006 - 08:04:14 - IngoMuellerYou are here: TWiki > Controls Web > SignalNamingConv

Convention for Signal Names

Starting with the preparations for the MLS control system (Willy-Wien-Lab) we have agreed on a soft convention about signal names, i.e. the part of EPICS record names that follow the last colon. The naming convention for the first part of a record name (Device Name) is described in BESSY's Device Naming Convention document.

The status of this convention is a strong suggestion. Creating signal names that do not follow these rules has to be well-justified (and the reasons documented).

Signal Names will have multiple parts. This convention will give guidelines for the first parts of a signal name, defining the follwing (end) part of the name will always be left freely to the database designer.

General Style Rules

Separation between parts of the Signal Name should be done by using upper case characters in the middle of the name. Do not use underscores ("_") or dashes ("-") to separate name parts. For the first name parts under this convention upper case separation is mandatory, for the free part it is strongly advised.

For some signals (e.g. single bit status channels) the second part (Signal Item) is not mandatory. Nevertheless - in all cases the database designer should use both defined parts if possible, as this makes name parsing, finding channels in the archiver, and similar tasks much easier.

First Part: Signal Type

The Signal Type specifies the type of signal in terms of function, direction of data flow, and value type (analog/digital). The first table contains types for channels that are part of a devices' public interface, the second table applies to channels that are internal to complex databases.

Public Channels

Tag	Name	Attributes
set	set point	analog, to device
rdbk	readback	analog, from device
cmd	command	command executed by device, to device
sel	mode select	select one-of-many mode, to device
stat	status	binary (single or one-of-many), from device

Private Channels

Tag	Name	Attributes
var	variable	passive record to just store stuff
mbox	mailbox	similar
buf	buffer	similar, for arrays
calc	calculation	calculation of values
cnt	counter	counting time or events
fwd	forward	forward values between records
sel	select	select a mode or position
in	input	raw value, from device
out	output	raw value, to device
raw	raw value	raw value, bidirectional
bits	bitfield	raw value, multibit (mbbiDirect, mbboDirect)
map	mapping	bit mapping

Second Part: Signal Item

The Signal Item specifies the kind of item or value that the signal consists of. While the Signal Type describes the signal in term of control system features, the Signal Item gives a hint to the physical (or physicist) meaning of the value. The first table contains Signal Items for digital signals, while the second table is meant to describe analog kinds.

Digital Channels

Tag	Name	Attributes
Pwr		device mains power
Access		access mode (local/remote)
Reset		reset command
Trig	Trigger	triggered devices
Gate		gated devices
Switch	Switch	read a hardware switch
Door		door status
Ilock	Interlock	interlock signal
Relay		relay state
Watchdog		watchdog status
Detect		detector status
One-of-Many Signals
Outp	Output	output selector
Pos	Position	position selector
Runmode		run mode
Single "Error" Bits
Over		exceeding an upper limit
Under		exceeding a lower limit
Range		out of range
Tol	Tolerance	out of tolerance
Valid	Validity	signal is valid
Ground		ground fault
Fail	Failure	failure
Break	Circuit Breaker	circuit breaker status
Leak	Leak Detector	leak detector status
Replace		notification to replace something

Analog Channels

Tag	Name	Attributes
Angle		angular sensors
Curr	Current	all kinds of electrical currents
Ampl	Amplitude	signal amplitude
Field		magnetic and electric field strength
Flow		mechnical currents: air or water flow
Freq	Frequency	generators
Delay		pulse delay
Width		pulse width
Gap		undulators
Level		all kinds of levels and thresholds
Press	Pressure	pressure sensors
Shift		undulators
Temp	Temperature	temperature sensors
Time		time (absolute and relative)
Timeout		timeout
Count		counter value
Volt	Voltage	electrical voltage
Power		electrical Power

Strings

Tag	Name	Attributes
Str	String

Examples

Just some examples to give an idea of the intentions...

Name	Description
cmdPowerOff	command to switch device OFF
cmdPowerStandby	command to switch device STANDBY
cmdPowerOn	command to switch device ON
selRunMode	select run mode
statRunMode	run mode status
statReplaceBottle	"Replace Bottle" indicator
calcCmdWord0	internal calc to combine command bits
outCmdWord0	output rec connected to HW that writes the command word
inStatWord2	input rec connected to HW for status word
statPower	power status: ON/STANDBY/OFF
setVolt	ps: voltage setpoint
rdbkVolt	ps: voltage readback
rdbkCurr	ps: current readback
rdbkTemp01	temperature readback
rdbkTemp02	dito
setLevelOverflowAlarm	sets the threshold for signalling overflow
setTimeout	sets a timeout (start) value
cntTimeout	timeout counter
varSelectionMask	selection mask buffer (seq.SELL points to this)

Additions

This convention is not fixed nor finished!

If you find you have to name a channel and you don't see a way to generate a name with the existing tags, feel free to suggest extensions to these tables. We should discuss suggestions at one of the regular group meetings and collaborate to make these naming conventions work for everyone.

-- RalphLange - 13 Apr 2006

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