Publication 1756-UM514B-EN-P - February 2003
11-2 Block Transfers with the 1756-DHRIO Module
Block Transfer
‘Pass-Through’ Messages
DH+ ‘Block Transfer (BT) Pass-Through’ messages are specific DH+
(PCCC) messages sent to an remote I/O channel, where it causes an
remote I/O Block Transfer.
To target a DH+ ‘BT Pass-Through’ message to an remote I/O channel
on a 1756-DHRIO module, the final destination of the DH+ message
must be the 1756-DHRIO module with the remote I/O channel.
In the case of Local DH+ Messaging, the bridging 1756-DHRIO
module must have its default slot configured to match the location
(slot) of the final destination 1756-DHRIO module (module with the
remote I/O channel).
In the case of Remote DH+ Messaging, the destination link ID and
destination node of the DH+ message must be set to the final
destination 1756-DHRIO module (module with the remote I/O
channel).
For example, if the target is an remote I/O channel on a 1756-DHRIO
module in slot 5 of a ControlLogix chassis and remote DH+ messaging
is used, the destination link ID is set to the ControlLogix chassis link
ID and the remote destination node is set to 5.
Block Transfer Examples
IMPORTANT
To send DH+ ‘Pass-Through’ messages to a
1756-DHRIO module, the module must be
configured with a valid routing table, as described in
Chapter 2, even if both channels are configured for
remote I/O.
IMPORTANT
In the examples in this chapter, only channel B is
connected to remote I/O. You can connect both
channels to remote I/O simultaneously if necessary.
If only one channel is connected to remote I/O, it is
recommended that you use channel B. If you
connect channel A to remote I/O, you cannot use
the programming terminal on the front of the
1756-DHRIO module.
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