GE PACSystems RX7i, User Manual

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Chapter 6. Programming EGD Commands
GFK-2224Q January 2017 107
(Word 7) EGD Command Number: Word 7 requests that a masked write EGD exchange operation occur. If the
command is processed successfully, it will result in a data bit for a specified EGD exchange being written from
the client to the server.
(Word 8) Command Retry Time: Word 8 specifies the time (in milliseconds) the Ethernet Interface will wait
between retries when transferring the command. A total of four tries will be made to send the command. If no
response is received after the four tries (i.e. after four times the retry time value), an error status will be returned
in the COMMREQ status word. If the command retry is specified as zero, the default value of one second is used.
(Word 9) Bit Mask: Words 9 – 10 specify the individual data to be written to the remote EGD exchange. The
usage of the Bit Mask and Data are described in
Masked Write to EGD Exchange Bit Mask and Data Bits
, below.
Word 9 contains a bit mask that identifies a bit or bits within a data byte. The mask bit corresponding to each
data bit to be written is set to 1; all other bits are set to 0.
(Word 10) Data: Word 10 contains the data byte that contains the bit or bits to be written to the remote EGD
exchange. The individual data bits to be written are in the same position as the "1" bits in the Bit Mask (Word 9).
(Word 11) Remote EGD exchange – Exchange Signature: Words 11 contains the 16-bit exchange signature
value to be compared at the remote EGD device. For remote PLC’s, the exchange signature should be set to
zero if signatures are not being used. However, when signatures are enabled, the signature field can be set to a
non-zero value so that commands will only be executed if signatures match. In this case, mismatched
signatures will cause the command to return a failure status.
An EGD signature has the format
maj.min
, where
maj
is the major value and
min
is the minor value. The least
significant byte of this word indicates the minor value and the most significant byte indicates the major value.
For example, a value of 0xAABB refers to a
maj.min
value of 0xAA.0xBB.
EGD Signatures Enabled
Signature Comparison
Desired
Recommended with
RMS of EGD
User Specified
Signature
No No No 0 (Default - no check)
Yes No No 0 (Default - no check)
Yes Yes Yes Current EGD signature
(Words 12 - 13) Remote EGD exchange – Producer ID: Words 12 and 13 contains the 32-bit Producer ID of the
desired exchange at the remote EGD device. Word 12 contains the least significant 16 bits of the Producer ID;
word 13 contains the most significant 16 bits.
(Words 14 - 15) Remote EGD exchange – Exchange ID: Words 14 and 15 contains the 32-bit Exchange ID of
the desired exchange at the remote EGD device. Word 14 contains the least significant 16 bits of the Exchange
ID; word 15 contains the most significant 16 bits. For the Masked Write EGD Command, the exchange at the
remote device must be a Produced exchange.
(Word 16) Remote EGD exchange – Exchange Data Offset: Word 16 contains the 0-based byte offset of the
single data byte data containing the bit or bits to be overwritten in the data portion of the exchange at the
remote EGD device.
(Word 17) Remote Server - Network Address Type: Word 17 specifies the format of the remote PLC address.
Word 17 must contain the value 1. This indicates a dotted-decimal IP address expressed using a separate
register for each decimal digit.
(Word 18) Remote Server - Network Address Length: Word 18 specifies the length in words of the remote PLC
IP address in this COMMREQ Command Block. Word 18 must contain 4.
(Words 19 – 22) Remote Server - IP Address: Words 19–22 specify the four integers, one integer per word, of
the dotted-decimal IP address of the remote PLC to be accessed.