FANUC Robotics America GFK-1541B User Manual
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5
Allowable Data Types in Exchanges
Boolean type variables are not allowed; neither are Boolean-Array variables. If discrete point
references such as %I or %Q are used to define a variable, you must define them as Byte-Array,
Word-Array, or Dword-Array variables. This implies that a variable consisting of discrete point
references must be defined in blocks of 8 points if it is defined as a Byte-Array, 16 points if
Word-Array, and 32 points if DWord-Array. Discrete memory must be byte-aligned. Valid
memory types are listed later in this chapter.
Producer and Consumer Period Ranges
Producer and consumer periods may be configured to be between 10 milliseconds (2
milliseconds for the Series 90-30 CPU374) and one hour (inclusively). They should be
configured in increments of 10 milliseconds (2 milliseconds for the Series 90-30 CPU374). If
not, they are rounded to the next highest 10-millisecond increment during operation (2
milliseconds for the Series 90-30 CPU374). For example, a configuration value of 11 (intended
to be 11 milliseconds) will be treated the same as 20 ms by the Ethernet Interface (12
milliseconds for the Series 90-30 CPU374).
For the Series 90-30 CPU374, you may also configure the producer period with the value of zero.
A zero period is interpreted as producing the data "as fast as possible". For the CPU374, zero
period production is scheduled every scan or every 2ms, whichever is slower. In a PLC with rapid
scan times, scheduling a produced exchange at zero results in a very high load on the network and
on the Ethernet Interface, which may degrade overall Ethernet performance. Scheduling multiple
exchanges for a zero period in a PLC with a low scan time can result in the Ethernet Interface
being unable to produce all the required data.
Effect of Enabling User Interrupts
If user interrupts are enabled (applies to Series 90-70 only), the data values of a variable greater
than 256 bytes are not guaranteed to be “atomic” (or “coherent”, meaning their snapshot is taken
at the same instant). If atomic data transfer is desired for a variable within the exchange, disable
user interrupts or limit the size of the variable to 256 bytes or less.
Update Timeout Period
Set the update timeout period for the consumer to twice the producer period and at least 20
milliseconds greater than the consumer period. Otherwise, the PLC may occasionally falsely
report refreshment faults. Use zero for the update timeout period of a consumed exchange to
disable timeout detection.
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