UPD72042BGT NEC [NEC], UPD72042BGT Datasheet - Page 9

• Manufacturer Part Number: UPD72042BGT
• Description: LSI DEVICE FOR Inter Equipment Bus (IEBus) PROTOCOL CONTROL
• Manufacturer: NEC [NEC]

2.2 IEBus COMMUNICATION PROTOCOL
• Communication method: Half duplex asynchronous communication
• Multi-master method
• Broadcast function (one-unit-to-multiple-units communication)
• Two modes, each offering different transmission speeds, can be selected.
• Access control: Carrier Sense Multiple Access with Collision Detection (CSMA/CD)
• Communication scale
The IEBus is outlined below.
Caution For the PD72042B, as a protective resistance, connect a 180- resistor in series with the BUS–
All units connected to the IEBus can transmit data to every other connected unit.
Group broadcast
General broadcast : Broadcast to all units
Bus mastership priority is as follows:
1 Broadcast takes priority over ordinary communication (one-unit-to-one-unit communication).
2 Units having lower master addresses have a higher priority.
Number of units
Cable length
Load capacity
Terminating resistance
Mode 0
Mode 1
and BUS+ pins.
Approx. 3.9 Kbps
Approx. 17 Kbps
f
X
= 6 MHz
: Broadcast to a specific group of units
: 50 max
: 150 m max (when twisted-pair cable is used <resistance 0.1
: 8000 pF max <between BUS- and BUS+>, f
: 120
7100 pF max <between BUS- and BUS+>, f
Approx. 4.1 Kbps
Approx. 18 Kbps
f
X
= 6.29 MHz
Data Sheet S13990EJ3V0DS
Maximum number of bytes
transmitted (bytes/frame)
16
32
X
X
= 6 MHz
= 6.29 MHz
/m or less>)
PD72042B
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