1–17Overview
Publication
17476.6 - July 1996
Complementary I/O Application Considerations
If you configure a complementary device to use more I/O image
space than an associated primary device, then block transfers can
only be performed to locations in the complementary device that
have associated I/O image space in the primary device. For
example, if a primary device is 1/2 logical rack and a complementary
device is a full logical rack, block transfers can be performed only in
the first 1/2 logical rack of the complementary device. Attempting
block transfers in the last half of the complementary device will
result in a BT error (error 11 – device not configured).
Word
7
Word 5
Word 6
Word 3
Word 1
Word 2
Word 0
Word 4
Logical
Rack 8
Word
7
Word 5
Word 6
Word 3
Word 4
Word 1
Word 2
Word 0
Logical
Rack 0
1/2 logical rack
configured and
usable
1/2 logical rack not
configured
1/2 logical rack
configured and usable
1/2 logical rack
configured, but not
usable for BT since
Words 4-7 are not
configured for the
primary device.
Complementary 1771 I/O Module Details
Use the following modules in either primary or complementary I/O
chassis opposite any type of module:
• Communication Adapter Module (1771-KA2)
• Communication Controller Module (1771-KE)
• PLC-2 Family/RS-232-C Interface Module (1771-KG)
• Fiber Optics Converter Module (1771-AF)
• DH/DH+ Communication Adapter Module (1785-KA)
• DH+/RS-232C Communications Interface Module (1785-KE)
Use the following modules in either primary or complementary I/O
chassis opposite any type of module. However, these modules do
not work as stand-alone modules; each one has an associated master
module. Use care when placing the master modules in the I/O
chassis:
• Analog Input Expander Module (1771-E1, -E2, -E3)
• Analog Output Expander MOdule (1771-E4)
• Servo (Encoder Feedback) Expander Module (1771-ES)
• Pulse Output Expander Module (1771-OJ)
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