Chapter 5. Ethernet Global Data72 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual GFK-2224QValid Memory Types for Ethernet Global DataThe PLC memory types listed below can be included in EGD exchanges.Memory Type DescriptionP-ProducerC-Consumer%R Register memory in word mode P/C%W Word memory in word mode P/C%AI Analog input memory in word mode P/C%AQ Analog output memory in word mode P/C%I Discrete input memory in byte mode P/C%Q Discrete output memory in byte mode P/C%T Discrete temporary memory in byte mode P/C%M Discrete momentary memory in byte mode P/C%SA Discrete system memory group A in byte mode P/C%SB Discrete system memory group B in byte mode P/C%SC Discrete system memory group C in byte mode P/C%S Discrete system memory in byte mode P%G Discrete global data table in byte mode P/CSymbolic Variables Symbolic variables P/CDiscrete point references such as %I or %Q are configured as Byte-Array, Word-Array, or Dword-Arrayvariables. That means a variable with discrete point references must be defined in blocks of 8 points if it isdefined as a Byte-Array, 16 points if Word-Array, and 32 points if Dword-Array. Discrete memory must be byte-aligned.Boolean type and Boolean-Array variables are not allowed.To use a symbolic variable in an EGD exchange, it must exist in the Variables definition for the target. To add itto an exchange, double click the Variable field to open a selection dialog box.Figure 35: Adding Symbolic Reference to Ethernet Global Data ExchangePlanning ExchangesIt is possible to configure more Ethernet Global Data than a PLC can transfer (especially on 10Mbit networks). Ifhigh levels of consumer timeouts occur in some or all of the consumed exchanges, the EGD load can bereduced by:▪ Increasing the production period (especially if the period is more frequent than double the minimum time inwhich the data is needed).▪ Defining fewer exchanges, each with more data.
