Owner's manual

Table Of Contents
3-4 Equipment-to-Host Messages
3.1.1.2 Communications States
The current communication state will be one of the values specified in Table 3-2. There is no variable
indicating the communication state. The communication state is presented to the Operator on the main
Operator interface screen.
Table 3-2 Communication State Values
Value Description
DISABLED The SECS link to the Host is disabled at the Equipment. The
Equipment will send no messages to the Host. The Equipment
will not respond to a Host-initiated ENQ.
ENABLED When communications are Enabled, the Equipment’s intention is
to be in communication with the Host. Whether or no the
Equipment is currently communicating with the Host determines
which sub-state of the Enabled super-state the Equipment is in.
ENABLED/COMMUNICATING The SECS link between the Equipment and the Host is operating
normally.
Periodically, the Equipment will send a “Heartbeat” message
S1F1 to ensure that the link is still operating. The heartbeat
frequency is controlled by equipment constant “HEARTBEAT”.
“HEARTBEAT” (VID 26) can range from 0 to 32000, with default
value 30.
If the Equipment encounters a SECS-I Retry Limit (RTY) error
when attempting to send a block to the Host, it discards any
messages queued for send and the communication state transits
to ENABLED.
ENABLED/NOT
COMMUNICATING
The SECS link to the Host is enabled at the Equipment, and the
Equipment is attempting to determine if the link is active. The
Equipment periodically sends S1F13 (Establish Communications
Request). If the connect is not successful for any reason, the
Equipment will try again periodically forever. The time between
attempts is controlled by the equipment constant
“ESTABLISHCOMMUNICATIONSTIMER”. This variable
(VID 44) can range from 0 to 32000 seconds, with default of
60 seconds.
Once the Host has responded with S1F14 (Establish
Communications Acknowledge), the Communication State will
change to COMMUNICATING.
The Host can also attempt to establish communications by
sending S1F13. The Equipment will accept the message and
respond with S1F14 and the Communication State will change
to COMMUNICATING.
In ENABLED state, the Equipment will accept messages from
the Host, but will ignore any messages except S1F13 and
S1F14. The Equipment will respond to the S1F13 while the
Communication State is ENABLED or COMMUNICATING,
but it will not send S1F13 once communications have been
established.