Sharp JW-21MN manual 16-4, Cause Countermeasure

- If the bus cable between the slave station 05(8) and 06(8) is disconnected in the following system.

03(8)	02(8)	01(8)	04(8)	Master	05(8)	06(8)	07(8)
				station
				B A	C	D
					Disconnection
State of an individual communication flag
D7 6	5	4 3 2	1 D0
OFF		Unstable	OFF

Remove the connector on point A, and turn ON the termination resistance of the master station.

As the communication possible stations 03(8), 02(8), 01(8), and 04(8) are normal, the state of communication monitoring flag is as follows.

D7 6 5 4 3 2 1 D0

OFF ON

Connect the A connector, and	As the one side of the termination
then remove the connector on	resistance is lost, all of the
point B.	communication possible stations 05(8),
	06(8), and 07(8) are abnormal, and the
	station 05(8) is unstable.
	D7 6 5 4 3 2 1 D0

16

Remove the connector on point C and make sure the B connector is not connected. Turn ON the termination resistance of the slave module 05(8).

Connect the C connector and make sure the B connector is not connected, and remove the connector at the next point to the point D.

Turn OFF the termination resistance of the slave station 05(8), and turn ON the termination resistance of the end station 06(8).

OFF Unstable OFF ON

As the communication possible station 05(8) is normal, abnormal points exists ahead of the point C.

D7 6 5	4 3 2	1 D0
OFF ON	OFF	ON

As the one side of the termination resistance is lost, the station 05(8) and 06(8) become communication possible stations, but the station 05(8) is unstable and the station 06(8) is turned to OFF, so the abnormal states occur between the point C and the point D.

D7 6 5 4 3 2 1 D0

OFF Unstable OFF ON

Cause	Countermeasure
Disconnection in the bus cable and the	Remove both the bus cable and
branch cable between the station 05(8) and	the branch cable connectors. After
06(8), or contact failure of the connectors	that, shorten one of these
	connectors and check conductivity
	using a tester.
Error on the slave station 06(8)	Exchange the slave module.

16-4