Trouble with ProSoft MVI56E-MNETR

Hello. I have a problem with ProSoft MVI56E-MNETR. I use 11 modbus devices connected to this module. If some of the devices fail, than the response time of correctly working devices grows significantly. I've tried all the possible combinations of settings in ProSoft Configuration Builder, but it didn't help. Can you give me some advice of how to solve this problem? Can I turn off reading commands for failed devices directly from RSLogix 5000 using software?

Subscribing because we're also having response time issues with systems using Prosoft MVI modules. Already converted several drives to hardwire control. We've been blaming the cheap drives but your post has me wondering if there might be something going on with the Prosoft end.......

I have had so little success with the Prosoft modbus cards, it is comical. Their tech support was no help, either. I always had the problems where if a device was turned off, transmit/receive time would sometimes increase to over 5 seconds. I gave up on them many years ago. I've been using the Red Lion Data Station Plus, and have never looked back.

In my case, the time increases from 3 to 30 seconds. Changing ARP Timeout and Response Time didn't help. As I understand if ProSoft module doesn't see devices then it use default setting and ARP Timeout is installed by 30 second.

Post the exact parameters you've been adjusting, and maybe an example of your Prosoft Configuration Builder application.

It would be even better if you had some Wireshark traces of the traffic on the network so you could measure the timeout and retry times, rather than estimating them.

It sounds like you've got a hypothesis: the MVI module doesn't correctly apply the TCP or ARP timeouts.

OK, that's possible. I've seen similar problems with communication modules (yeah, I'm looking at YOU, DeltaV) that the vendor was unaware of or didn't want to change or fix.

Thanks to the ubiquity and ease of use of Ethernet and Wireshark, really good diagnostic information and troubleshooting procedures are easy to come by. It would be a shame not to use them.

Johnny..

A couple of things.. First, the MNETR only has a single client. So when devices don't respond, the client needs to wait and retry according to the settings. The bad thing about this is the MNETR doesn't know if the IP changed, or the device just isn't there, so it issues an ARP to resolve the IP to the MAC.

In your situation, here's what I would do:
Set the timeout to 50ms (the actual response is probably around 5ms, so you should be fine)
Set the retries to 0 or 1
Set the ARP Timeout to 1
Set the Command Error Delay to 0

Next, there is the Static ARP Table... this is used for situations just like this - devices get turned off/on periodically, which causes ARP delays. This is where you define the MAC and IP for a particular device. Once done, the module will no long issue ARP commands for the device.

Thanks for the answer.

Hello,

I have same problem: I use 7 modbus devices connected to this module. When one module failed, the time between connections increase some seconds; in my application I can not have this time between communications.

I already use ARP static table but without results.

Any sugestion?

Thank you.

rffp..

There is a setting called "command error delay" - What this does is delay a command from executing if this same command failed previously. If you set "command error delay" to 0, and are using static ARP, there should be no delay between commands, whether they fail or not.

ProSoft support advised me reflash my MNETR on MNETCR, because MNETCR is multi-client device. Also, MNETCR lets to manage Modbus devices directly from RSLogix 5000 using software.