Understanding The Block Transfer Status Word - Allen-Bradley 1203 Series User Manual

5–2 Using Block Transfer Messages
Understanding the Block
Transfer Status Word
Bit 17 Bit 16 Bit 15 Bit 14 Bit 13 Bit12 Bit 11 Bit 10
BT Write Available
Status Bit 15
BT Wait
Status Bit 13
BT Read Data Available
Status Bit 12
BT Write In Progress
Status Bit 11
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The block transfer status word is returned from the Remote I/O
module. It is the first word associated with the rack in the controller
input image table. This status word indicates the condition of the
Remote I/O module itself and is not part of the standard block transfer
instructions in the ladder program. Figure 5.1 details the individual
bits.
Figure 5.1 Remote I/O Status Word
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Status
Block Transfer The SCANport product and Remote I/O module are communicating and are
Ready ready to process block transfers.
Block Transfer A block transfer write is in progress between the controller and Remote I/O
Write in module. This bit is cleared when the data transfer to the module is complete.
Progress
Block Transfer The Remote I/O module has data available for the controller to read.
Read Available
Block Transfer The Remote I/O module is communicating with the SCANport product. This
Wait bit is cleared when the data transfer between the module and SCANport
product is complete.
Block Transfer An error has occurred during communications with the SCANport product, or
Error the BTW data is invalid.
Block Transfer The Remote I/O module is ready to receive a Block Transfer Write.
Write Available
Figure 5.2 Bit Timing
BTW data at
BTW
Request Remote I/O Module
Reserved for future use.
Block Transfer Ready (BT_READY)
Block Transfer Write in Progress (BTW_IN_PROG)
Block Transfer Read Available (BTR_AVAIL)
Block Transfer Wait (BT_WAIT)
Block Transfer Error (BT_ERROR)
Block Transfer Write Available (BTW_AVAIL)
Reserved for future use.
Reserved for future use.
Description
BTR
BTW
Request
Complete