PSC PowerWedge 10, Руководство пользователя

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Programming the PowerWedge 10
31
PowerWedge
®
10
In EOR-only protocol, a record consists of data characters followed by the
end-of-record (EOR) character. (The Xon/Xoff command characters are
received with no EOR character appended.) When the protocol parameter
is set to 00 (EOR only), the data records are received according to both
the EOR-character (I.D. #CC) and timeout (I.D. #CD) settings. Records
received with the EOR character appended are processed immediately. If
the timeout setting is between 01 and 99 (10 to 990 milliseconds), then
the data is processed if either an EOR character is received or a timeout
occurs.
In ACK/NAK protocol, a record consists of data characters followed by the
end-of-record (EOR) character and a check character. This protocol trans-
mits and receives ASCII ACK/NAK (ACK = 06h, NAK = 15h) characters
for data integrity control.
A data record must have an EOR character and a check character (mod
256 sum of all data characters and the EOR character) appended to be
considered good. (The EOR-character setting, I.D. #CC, cannot be 00.)
If the record is good, an ACK character is transmitted to inform the host
that the data arrived successfully. If the record is bad, a NAK character is
transmitted to the host.
If the NAK character is received or a timeout occurs, the data record is
retransmitted. Up to ten attempts will be made. If a communications error
occurs, a nine-beep error signal is issued and the decoder is reset.
The interfunction delay setting (I.D. #BE; the default is 00) determines
the delay between the receipt of the data record and the transmission of
the ACK/NAK response. The length of time the decoder will wait before
checking for a valid record after each character is received is determined by
the timeout setting.
Code 39 and ASCII Equivalents for Serial
Characters
Table 2 provides Code 39 and ASCII equivalents for serial characters. For
Code 39, ASCII, and mnemonic equivalents of keyboard keys, see
Full Keyboard Support on page 81
.