Device Data Transfer function on NS8 HMI.

[Andy_P 7]

I have a project coming up that will involve two PLC's (prob CJ1M) connecting to a single NS8 HMI via NT-Link (1:N High speed) on each of the serial ports. There will also be a need to have some amount of communication between the two PLC's. This will be a departure for me because usually I only have one PLC and one HMI in a system. I have discovered the Device Data Transfer function on the HMI and on first glance it would appear to be the perfect way to do this. I don't anticipate having a huge amount of comms between the two units: perhaps a block of 200 words or so on a specific trigger, and maybe 10 words on a 100mS cyclical basis. (Pretty vague specs at the moment, I know!) Would this be doable, bearing in mind that the comms is via the two serial links? Is there much latency bewtween requesting data from one host and receiving it in the other for example? I'm thinking it will be OK, but not had a chance to experiment yet, so if anyone has any experiences with this function (good and bad), it would be great if you could share them. Thanks.

[banker 2]

Hi Why not go for the CJ2M with ethernet. It has Ethernet/IP build in. Very easy to setup data exchange between the 2 plc. Banker

[Andy_P 7]

Good point, didn't think about that. No experience with that either yet though. Simply a case of a single ethernet cable directly connecting each PLC and then configuration? No ethernet switch involved? If that is so, then it keeps my options open if I go for CJ2M's instead.

[banker 2]

Hi You can use a connection without a switch but better go for an installation with a switch and connect the NS panel on ethernet also. Nice an simpel, one connection for all 3 devecies. You will need Omron Network configurator for setting up the 2 plc. It is very easy. Make some Network var. in cxp as in and out. and done!!!. There is also a "guide" on myomron.com. Banker

[Andy_P 7]

Good stuff, thanks for your suggestion. Always good to have an alternative and it has given me some food for thought.

[BobB 58]

Use an Omron switch - I do - easy to mount (DIN rail) just requires 24VDC power supply. Ethernet IP is the easiest thing to set up with Omron - just watch the total number of words available with the built in Ethernet port - 640 words if I remember correctly. They have to protect their market with the more expensive rack mounted module!

[Andy_P 7]

Thanks Bob, had no idea that Omron produced a switch, will have to investigate. 640 words should be more than enough for this project, but good to know the limit nonetheless.

[banker 2]

Bob this "omron" switches are double price than other industrial DIN rail 24 V switch. BTW. the first CJ2M Ethernet had a limit of 40 word in/out if i remember correct. Banker

[BobB 58]

I think the limit is 640 words on the network - individual PLC limit I think is 80 words with the V1.2? processor. The earlier ones were less words per PLC. I also understand there is a firmware update available from Omron to enable the higher word count. I have a job running at the moment where I have 1 x CS1D and 4 x CJ2M-CPU33. The network has been set up for the addition of another 10 PLCs at a later date. I have allocated 40 words per PLC. I did not think the price of the switch was too bad to be honest - using the high end one too which has a fault contact. Do not like commercial ones which are cheap and the other options for industrial grade in Ozz are pretty much the same or more.