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The I/O ENABLED LED on my Genius block is off or blinking erratically. What does it mean and how do I correct the condition?

November 27th, 2018

This LED turns off when the Genius block has not communicated with Genius Bus Controller (GBC) for 3 bus scans. This condition can be caused by several things.

The PLC CPU is stopped. Check this first.

There is a problem with the Genius bus cable. Review the following items:

Verify that the Genius bus cable is of the same type and manufacturer throughout that particular Genius bus. Mixing cable type and manufacturers on the same Genius bus can cause erratic communication between the Genius block and the GBC. Also, make sure that the cable in use is one of the cables listed in Chapter 2 of GEK-90486-F1 (Visit our Genius Manuals page or an equivalent cable to one of those listed.

Verify that the terminating resistors are properly matched to the cable in use and are located at both ends of the Genius bus. Also, make sure that the termination resistors are not wire-wound resistors. Improper termination can cause erratic communication between the Genius block and the GBC. Information on terminating resistors can be found in Chapter 2 of GEK-90486-F1 or an equivalent cable to one of those listed.

Verify that the cable is properly installed. This includes:

The same wire within the twisted pair goes to the same terminal on each Genius device, including the GBC. For example, if one wire in the pair has black insulation and the other wire has yellow insulation and the black-insulated wire is connected to “Serial 1” on the GBC, it should go to the “Serial 1” connection on every Genius device on that bus. The other wire in that pair (yellow) should be connected to “Serial 2” on every Genius device on that bus. Keep in mind that different cables use different color combinations and this is an example only.

Verify that the shields are properly connected. Typically, “Shield Out” on a Genius device located at one end of the Genius bus is connected to “Shield In” of the next downstream device and this pattern is repeated as you go from device to device until you reach the other end. (It is legal to start with “Shield In” and connecting it to “Shield Out” of the next device and repeating this pattern also.) If the shields are not properly connected, ground loops and/or ineffective shielding can result.

Verify that all connections are solid and keep splices to a minimum, preferably none.

Verify that the Genius bus cable is routed properly. While Genius busses are robust and are resistant to electrical noise, it, like most field busses, is not totally immune to electrical noise, especially strong noise sources like arc welders.

Verify that the Genius block is properly grounded.

The data rate on the Genius block is set to the wrong data rate (does not match the bus). Remove the block from the bus, place a terminating resistor between “Serial 1” and “Serial 2” and use the HHM to correct the data rate.

The Genius block is defective.

 
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