
User’s Manual U16541EJ4V0UD
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CHAPTER 18 IEBus CONTROLLER
IEBus (Inter Equipment Bus) is a small-scale digital data transfer system that transfers data between units. To
implement IEBus with the V850ES/SG2, an external IEBus driver and receiver are necessary because they are not
provided.
The internal IEBus controller of the V850ES/SG2 is of negative logic.
The following models of the V850ES/SG2 have an on-chip IEBus controller.
PD703270, 703270Y, 703271, 703271Y, 703272, 703272Y, 703273, 703273Y, 70F3271, 70F3271Y, 70F3273,
70F3273Y
18.1 Functions
18.1.1 Communication protocol of IEBus
The communication protocol of the IEBus is as follows.
(1) Multi-task mode
All the units connected to the IEBus can transfer data to the other units.
(2) Broadcasting communication function
Communication between one unit and multiple units can be performed as follows.
Group-unit broadcast communication:
Broadcast communication to group units
All-unit broadcast communication:
Broadcast communication to all units.
(3) Effective transfer rate
The effective transfer rate is in mode 1 or mode 2 (the V850ES/SG2 does not support mode 0 for the effective
transfer rate).
Mode 1: Approx. 17 kbps
Mode 2: Approx. 26 kbps
Caution
Different modes must not be mixed on one IEBus.
(4) Communication mode
Data transfer is executed in half-duplex asynchronous communication mode.
(5) Access control: CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
The priority of the IEBus is as follows:
<1> Broadcast communication takes precedence over individual communication (communication from one
unit to another).
<2> The lower master address takes precedence.
(6) Communication scale
The communication scale of IEBus is as follows.
Number of units: 50 MAX.
Cable length:
150 m MAX. (when twisted pair cable is used)
Caution
The communication scale in an actual system differs depending on the characteristics of the
cables, etc., constituting the IEBus driver/receiver and IEBus.