Hardware/Software

Chapter 3
Configuration & Interfacing
3–25
MCA Status Word The status word is returned from the MCA Board to the PLC Controller in
addition to the Block Transfer Status Byte (Word 4, high byte). The MCA
status word appears as the first slot (or word) in the rack assigned to the
Multi-Communications Adapter (Refer to Figure 3–17). This status byte
indicates the condition of the MCA itself and is not included as part of the
PLC Controller block transfer instruction. However, individual bits from
this word are used in the PLC Controller program to control block transfer
instructions to the Drive. Refer to the block transfer example for proper
use of these bits.
Figure 3-17. DCST A TUS - Adapter Status W ord Description
PLC Controller Digital Communications Adapter
Rack 0
Rack 1
Rack 2
•
•
•
Rack U
Input Image
T able
Rack #2
DC STATUS
Word 1
Word 2
Word 3
•
•
•
Rack U
Decimal
Octal
15 14 13 12 11 10 9 8
17 16 15 14 13 12 11 10
7 6 5 4 3 2 1 0
7 6 5 4 3 2 1 0
BIT
Block Transfer Error (BT_ ERROR)
Block Transfer Wait (BT_ WAIT)
Block Transfer Read AVAIL (BT__ RD __ DATA __ AVAIL)
Block Transfer Write in Progress (BT__ WR __ IPROG)
Block Transfer Ready (BT__ Ready)
Channel in control when MCA is in Redundant mode.
Status Word Bit Definitions Block Transfer Ready – Indicates that the Drive is ready to process and
receive block transfer requests.
IMPORTANT: Do not attempt to send block transfer requests to the Drive
if this bit is not set. The Drive will not respond to the request.