HORNER HE800JCM200, Руководство пользователя

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PAGE 18 14 MAY 2002 CH. 3
MAN0484-01
Number of Words:
This value represents the number of words from the PGN data to store into %AIs. A
PGN could contain 8 words of data. If only the first 4 words are needed then this value would be set to 4.
(Requires a number to be entered between 1 - 50.)
Starting Word: This value represents an index into the PGN data. Currently, this value is fixed a 1 so
the PGN data starting at word 1 through the Number of Words will stored to %AIs. If the desired PGN
data word is at word 6 then Number of Words would set at 6 (PGN data word 1 – data word 6 would be
stored to %AIs).
In the future, this value may be adjustable, which would allow for starting at PGN data word 2 or higher.
f.
Scan Method: The Scanning method uses a scan table that contains a series of PGNs and
associated information. Data for the configured PGNs is continuously gathered and sent to the PLC.
There are two modes for gathering data from devices on the J1939 network, monitor and request. Each
PGN in the scan table is configured to use one of the two modes for gathering data. It denotes the
method used to scan and obtain PGN values.
Monitor Mode
If the Engine Control Module broadcasts a desired PGN’s data on a regular basis, then the mode
for that PGN is configured for monitor.
Monitoring does not require interaction between the JCM200 and a device on the network. The
JCM200 monitors the network for the PGNs that are configured as monitor mode in the scan
table. If it finds a match, then the data is sent to the PLC.
Request Mode
If the desired PGN is not sent on a regular basis, then a request must be made from the JCM200
to the device
before the data is sent. The mode for these PGNs are configured for request.
Requesting requires interaction between the JCM200 and a device on the network. The JCM200
must send a request message to a device onto the network and receive a reply
before that data
can be sent to the PLC.