FANUC Robotics America GFK-1541B User Manual
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Monitoring the Channel Error Bit
This bit (normally 0) is the primary indicator for an error on a channel. It indicates any channel
error, fatal or non-fatal. It does not necessarily indicate that the channel is down (idle). If this bit
indicates an error:
Initiate the Abort command and then reinitiate the Read or Write command, or if the error
persists,
Initiate the Retrieve Detailed Channel Status command to find out if the channel is down and
possibly why it went down.
Keep in mind, however, that the status code may change from between the time the Channel Error
bit indicates an error and the time the Retrieve Detailed Channel Status command retrieves the
code.
The Channel Error bit for a channel is not meaningful until after the Ethernet Interface updates
the CRS word confirming the Read or Write command for that channel. In the case of an
Establish Channel command, the CRS word is updated before the Channel Error bit is set to 1.
Monitoring the Data Transfer Bit
Typically you will set up a channel to perform repetitive reads or writes. The Data Transfer bit
pulses ( 0
→ 1 → 0) each time there is a successful read or write. This can be an indicator to
the ladder program to move the most recent data to another location.
The Data Transfer bit for a channel is not meaningful until after the Ethernet Interface updates the
CRS word confirming the Read or Write command for that channel.
Do not use data received from a server until the CRS word confirming the Read command for that
channel is 1 or the Data Transfer bit goes to 1. Do not assume that when the Data Transfer bit
goes to 1 that a transfer has just completed during the last scan
. The Data Transfer bit is not
closely synchronized in time with the transfer. The bit only indicates that a transfer has occurred
in a past scan. A rising edge on the Data Transfer bit indicating that a transfer has completed
successfully does not guarantee that the next transfer has not begun or completed.
Sequencing Communications Requests
If the Ethernet Interface receives Command Blocks from the PLC CPU faster than the Interface
can process them, the Interface will log an exception event 08, Entry 2=0024H and will log the
PLC Fault Table entry:
“Backplane Communications with PLC Fault; Lost Request”
Only one COMMREQ function per channel can be pending at one time. A COMMREQ function
is pending from the time it is initiated in the ladder program until its CRS word has been updated
to a non-zero value by the Ethernet Interface.
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