SECS GEM Manual - 第50页
GEM Manual for DEK Printers Capabilities Issue 1.6 January 22, 2018 Page 50 of 171 The deadband is a key concept of limits monitoring, e specially for floating point variables. Its purpose is to prevent a phenomenon know…
GEM Manual for DEK Printers Capabilities
Issue 1.6 January 22, 2018 Page 49 of 171
4.10.2 Monitoring Limit Characteristics
A limit is defined by a set of attributes that include the variable (VID) to which the limit corresponds,
the units of that variable, the maximum and minimum possible values of the limit (LIMITMAX and
LIMITMIN) and the specific borders of the limit (UPPERDB and LOWERDB).
There is a limitation to the values of UPPERDB and LOWERDB which may be stated as:
LIMITMAX>UPPERDB>LOWERDB>LIMITMIN
Example of how Limits can be applied to monitor a variable:
Limit 1
Limit 2
Limit 3
Limit 4
Limit 5
Limit 6
Limit 7
Nominal
Upper Spec. Limit
Lower Spec. Limit
Upper Control Limit
Lower Control Limit
Minimum Limit
Maximum Limit
A limit divides the possible range of variable values into two parts, the upper zone and the lower zone.
At any time, the monitored variable is considered to be in one and only one of these zones. However,
as these two zones have an area of overlap. This is called the deadband.
UPPER ZONE
LOWER ZONE
DEAD BAND
Event
Event
LIMITMAX
LIMITMIN
UPPERDB
LOWERDB
GEM Manual for DEK Printers Capabilities
Issue 1.6 January 22, 2018 Page 50 of 171
The deadband is a key concept of limits monitoring, especially for floating point variables. Its purpose
is to prevent a phenomenon known as chattering (the repeated changing of zones due to small, rapid
fluctuations in variable value while near the zone boundary). In practice, the value of a variable must
reach the opposite boundary of the deadband before a zone transition can occur. Thus, if a variable's
value reaches the UPPERDB and moves into the upper zone, it will not return to the lower zone until it
falls back to the LOWERDB. The difference between UPPERDB and LOWERDB should always be
greater than the typical amplitude of those fluctuations, which are deemed insignificant. In some cases,
the width of the deadband may set to zero (UPPERDB = LOWERDB). At first glance, this would
seem to make indeterminate the current zone when an integer value sits on the limit. However, this is
not the case, when movement of the value is considered.
To illustrate, an example is given, assuming that UPPERDB = LOWERDB = 100. The list shows
consecutive readings of the variable and the resultant zone:
99 Lower Zone (Initial reading)
101 Upper Zone (Zone transition)
100 Lower Zone (Zone transition)
100 Lower Zone
99 Lower Zone
100 Upper Zone (Zone transition)
Transition from one zone into another generates a collection event, as might be reported via S6F11.
The host has the option of receiving notification by enabling event reporting for the event. For each
variable that has monitoring capability, one CEID is reserved to indicate zone transitions for that
variable. To aid in the determination of the nature of a transition event, three DVVAL's have been
defined: LimitVariable, EventLimit and TransitionType.
Scenarios:
Host defines limit attributes:
Comments Host Equipment Comments
[IF] S2, F45 is Multi-block
[THEN] Send Multi-block inquire
S2F39 -->
<-- S2F40 Multi-block grant.
[END IF]
Host defines new variable limit
attributes
S2F45 -->
<-- S2F46 Equipment acknowledges Host request.
Host queries equipment for current limits:
Comments Host Equipment Comments
Host queries Equipment for current
variable limit attribute definitions
S2F47 -->
<-- S2F48 Equipment returns report containing requested
variable limit attribute values.
Examples of applying limits monitoring for different applications are shown in SEMI E30-95
Appendix 7.
GEM Manual for DEK Printers Capabilities
Issue 1.6 January 22, 2018 Page 51 of 171
4.11 Spooling
In the event that a communication failure occurs the DEK printer is capable of spooling messages into
non-volatile storage. These messages can be recovered for transmission when the communications link
is restored.
4.11.1 Definitions
MaxSpoolTransmit: An equipment constant containing the maximum number of messages that the
equipment will transmit from the spool in response to an S6F23 "Transmit Spooled Messages" request.
If MaxSpoolTransmit is set to zero, no limit is placed on the messages sent from the spool. Multi-
block inquire/grant messages are not counted in this total.
OverWriteSpool: An equipment constant used to indicate to the equipment whether to overwrite data
in the spool area or to discard further messages whenever the spool area limits are exceeded.
Send Queue: Refers to the queue into which equipment generated SECS messages are placed in
preparation for transmission to the host.
Spool: The spool is an area of non-volatile storage in which the equipment stores certain messages that
cannot be delivered to the host (when the equipment is in the NOT COMMUNICATING substate of
COMMUNICATIONS ENABLED).
SpoolCountActual: A status variable used to keep a count of the messages actually stored in the
equipment's spool area. Multi-block inquire/grant messages are not spooled and not included in this
count.
SpoolCountTotal: A status variable used to keep a count of the total number of primary messages
directed to the spool, regardless of whether placed or currently retained in the spool. Multi-block
inquire/grant messages are not spooled and not included in this count.
SpoolFullTime: A status variable containing the timestamp when the spool last became full. If the
spool was not filled during the last spooling period, this will contain a time value prior to the current
SpoolStartTime.
SpoolStartTime: A status variable containing the timestamp from when spooling was last activated.