25s interval time between plc tag value refresh

Ignition
1

I have a site siemens 400 plc. it is.connected to a wonderware scada at the moment.

I set up an ignition local gateway taking only 10000 tags, but the refresh time is 25+ seconds.

if i remove the tags to only 500, the refresh time is 2 seconds as per designed in tag group.

what is the possible solutions I should try to improve the comms speed? most of the tags are configured to 5s scan time.
It is a local ignition gateway with lan cable to the 400 plc.

2

there are 7349 tags in the gateway.
overload:
at 3584ms
1102%

at 5020ms
764%

at 7421ms
401%

at 8401ms
455%

Is it because simply the plc cannot handle the comms with two scada systems?
never have such issue with 1500 or compactlogix or m340.

3

That 's certainly what it looks like. Not surprising with such an old processor, I would think.

2 Likes
4

I'm not a Siemens guy, but the S7-400 supports a 480 byte PDU, while Ignition's default size is 240. That would help a bit.

2 Likes
5

Thank you for the hint.

I changed the value to 480 in the driver advance setting, the overloads are back to normal

Sampling time is around 4sec, which is acceptable to this project.