- 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 then remove the connector on point B.
As the one side of the termination resistance is lost, all of the 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
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
16 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. |
|
|