ELK M1 databus errors...

After reading the posts about database errors and resistance, I decided to look at my error rate.

My first check said T2A4 - 3031
then 7 hours later is was T2A5 - 3110
then 18 hours after the first check it was T2A3 - 3224

So there were 193 errors over 18 hours, all with different tags.

The wiring is pretty simple, there is on large 42" ELK can, then a 12" can above it and four 15" cans to the right of the ELK can.
The databus just goes through these cans picking up 5 input zones, one serail port and then the last can has a run to a keypad about 20 feet away that is terminated.

Then inside the ELK can is a databus hub retrofit. Which is wired in parallel to the M1 with the other bus.

I turned the system completely off, including disconnecting the batteries and measured the resistance at 117 ohms. So after a bit of a searching, I discovered the databus hub needed a terminator in the JP1 position, and with that installed my resistance measured 65 ohms.


I turn every thing back on and 18 hours later I get T2A4 - 223.

So, after 18 hours, I'm getting more errors than I was before with the missing terminator!!!

My bus wiring consists of CAT-5 cable using the blue/blue-white pair for power, and the green/green-white pair for the A/B of the bus.

My questions are:
What exactly do I keep getting different device units with the error count?
Why didn't my error count go down when I fixed the bus terminator?

Thanks.

Your data bus errors are not a big issue. The data bus errors are how many times the M1 had to retry a command to a peripherial device. It is not a perfect bus environment, but nothing to loose sleep over either. If you stand in front of the keypad when the data bus error screen is displayed and can see it count up maybe two or three a minute then you may want to look further into what is causing the errors.

Things that cause RS-485 data errors are:
Improperly terminated data bus. There should be a termination resistor enabled at the extreme ends of the bus run. Measure the resistance across data A and data B with the power OFF. I should read about 65 ohms +- 10 ohms.

Make sure you do not have branches running off the main bus. Everything should be in series wired.


T2 is an input expander, A5 is address 5, A4 is address 4...

Spanky said:

Your data bus errors are not a big issue. The data bus errors are how many times the M1 had to retry a command to a peripherial device. It is not a perfect bus environment, but nothing to loose sleep over either. If you stand in front of the keypad when the data bus error screen is displayed and can see it count up maybe two or three a minute then you may want to look further into what is causing the errors.

Things that cause RS-485 data errors are:
Improperly terminated data bus. There should be a termination resistor enabled at the extreme ends of the bus run. Measure the resistance across data A and data B with the power OFF. I should read about 65 ohms +- 10 ohms.

Make sure you do not have branches running off the main bus. Everything should be in series wired.


T2 is an input expander, A5 is address 5, A4 is address 4...

Click to expand...

Thanks for the info. Quick question, why does the device unit change as time goes by - is that the device that has the most timeouts?

How are you checking these errors? Is this a menu option in the keypad, or can it be done through ELKRP?

On the keypad, System Diagnostics. See Page 18 near bottom.

Okay, I finally checked my error count. I was so worried from reading some of the stories, I was a little afraid to.
Only 13 errors in 2~3 weeks. Lucky or did something right, either way, I'dbetter knock on wood just to be safe.

t2a2 = 2201. Hrm. Everything seems to be working fine though. t1a1 was zero.