Watch list binaries

b3charlie

Hey Joel,

I am wondering why my binaries drop out occasionally in my ten step program (with steps per step) in the watch list.

Mango is all modbus ip to some plc's. Would a packet collision cause this on the plant wide intranet/internet

I am having to go and "set" my 1's (reset) as they occasionally just zero off for no apparent reason

This is a mission critical issue...

Thanks, Charlie

dan

Gidday, have you tried some standard network tests like ping, to check out if there are any lost packets etc?


ping 192.168.1.254

Pinging 192.168.1.254 with 32 bytes of data:
Reply from 192.168.1.254: bytes=32 time=1ms TTL=255
Reply from 192.168.1.254: bytes=32 time=1ms TTL=255
Reply from 192.168.1.254: bytes=32 time=3ms TTL=255
Reply from 192.168.1.254: bytes=32 time=2ms TTL=255

Ping statistics for 192.168.1.254:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 1ms, Maximum = 3ms, Average = 1ms

If your not familiar with ping, you are looking for 0% loss over a period.
On windows you can use -t to make the ping go longer, then press CTRL BREAK to interrupt the ping to get an update on packetloss.

Or use a tool like smokeping to keep a log of latency to your hosts over time...

On the other hand, with Mango you could try increasing the timeout to the host, that might assist?

Cheers
Dan

Attachment: download link

JoelHaggar

Good suggestion Dan.

If it's a modbus data point and it changes from a 1 to a 0 I would assume that Mango received a 0 from the device. You could disable the data source and use the point locator test tool to verify the data from the device. I really doubt a packet collision would cause this and if it did it would be updated back to to the actual value on the next poll.

What is your polling rate? I would check the logging setting for the point and then also look at the history for the point and see if you can determine. But basically Mango is just displaying the data it gets from the device. Also check to see if you are getting read errors on the device.

Hope that helps,

Joel.

b3charlie

Thanks Dan

That's not the issue. The question posted has to do with watch list binaries.

loss of ip through data packet collision (in milliseconds) might be causing the preset binary drop out to my plc's
in Mango watch list, not sure yet...

Cheers
Charlie Campi

www.plcautomationcontrols.com

JoelHaggar

Charlie,

What do you mean by Watch List binaries?

I was assuming you mean binary points that you are viewing on the watch list?

Joel.

b3charlie

watch list binary,set on 1 off 0

All pre written oven control program with 10 cook steps

The 1's occasional revert to 0 for no apparent reason.

example:

Step 1

High fan = 1
low fan = 0

Intake damper = 1
exhaust damper = 1
Burner = 1

step 2...etc

JoelHaggar

Referring to something as a "Watch List Binary" doesn't make any sense within the Mango terminology.

The watch list is used to monitor a list of data points.

In your example please specify what type of data points they?

I'm guessing they are all Modbus IP?

Joel.

jeremyh

Would a packet collision cause this on the plant wide intranet/internet

The nature of how TCP works means that it is not really possible for packet loss, packet collision (is this the 90s?) or other network 'interference' to cause you to read a one as a zero.

I think it is far more likely that your script (or maybe some sneaky code in your PLC) is setting the bit to zero.

I am having to go and "set" my 1's (reset) as they occasionally just zero off for no apparent reason

So Mango can write to these points too? Is that necessary for your plant to function? Is it possible to make the point read-only and see if the issue still occurs?