Chapter 6. Programming EGD CommandsGFK-2224Q January 2017 97(Word 7) EGD Command Number: Word 7 requests that a read PLC memory operation occur. If the commandis processed successfully, it will result in PLC reference memory data being retrieved from the server to theclient.(Word 8) Command Retry Time: Word 8 specifies the time (in milliseconds) the Ethernet Interface will waitbetween retries when transferring the command. A total of four tries will be made to send the command. If noresponse is received after the four tries (i.e. after four times the retry time value), an error status will be returnedin the COMMREQ status word. If the command retry is specified as zero, the default value of one second is used.(Word 9) Local PLC - Memory Type: Words 9-11 specify the location in the local PLC where the EthernetInterface will store data received from the remote PLC. Valid values for Word 9 are listed below. The amount ofdata to be transferred is specified by the number of memory units of the data read from the remote PLC (Word15).Type Value (Decimal) Description%W 14 196 Word memory (word mode)%R 8 Register memory (word mode)%AI 10 Analog input memory (word mode)%AQ 12 Analog output memory (word mode)%I 1670Discrete input memory (byte mode)Discrete input memory (bit mode)%Q 1872Discrete output memory (byte mode)Discrete output memory (bit mode)%T 2074Discrete temporary memory (byte mode)Discrete temporary memory (bit mode)%M 2276Discrete momentary internal memory (byte mode)Discrete momentary internal memory (bit mode)%SA 2478Discrete system memory group A (byte mode)Discrete system memory group A (bit mode)%SB 2680Discrete system memory group B (byte mode)Discrete system memory group B (bit mode)%SC 2882Discrete system memory group C (byte mode)Discrete system memory group C (bit mode)%S 15 3084Discrete system memory (byte mode)Discrete system memory (bit mode)%G 5686Discrete global data table (byte mode)Discrete global data table (bit mode)(Words 10 - 11) Local PLC - Memory Starting Address: Words 10 and 11 determine the starting address in thelocal PLC in which the data from the remote PLC is to be stored. The value entered is the 32-bit offset (1-based)from the beginning of PLC memory for the memory type and mode specified in Word 9. Word 10 contains theleast significant 16 bits of the offset; word 11 contains the most significant 16 bits of the offset. This offset willbe either in bits, bytes, or words depending on the mode specified. (For example, if Word 9=16 and Words 10,11 = 2, 0 then the starting address will be %I9.) Valid ranges of values depend on the PLC’s memory ranges.The user is responsible for assuring that this area is large enough to contain the requested data withoutoverwriting other application data.(Word 12) Remote PLC - Memory Type: Words 12–14 specify the memory type and starting address in theremote PLC from which the data is to be read. Valid values for Word 12 are listed above.14 %W memory is supported on PACSystems clients and servers only.15 Read-only memory, cannot be written to.
