H0-Ecoms Not Talking

[91dresser]

I have two H0-Ecoms that I'm trying to get talking. They are both in 06 PLCs. They both have static IP address's assigned, the dip switches are set for the ID number, switch 7 is "on", and they're using an I-box RX to try and write an analog value from the master to the slave. The ethernet is a DHCP configuration. The PLCs are sitting in different buildings on different subnets. The gateway, subnet mask, & IP are correct.

I can take the slave PLC to master PLCs switch, change the IP, and the value is passed. Once I get two switchs between the slave and master all communications stop. I can see the PLCs with DirectSoft5 across the ethernet when they are in their respective locations. The IT folks say the network is fine. The programming all looks correct. I have two other PLCs (205/260/H2-ECOM100) on campus doing the same thing for years. The new setup programming is written exactly like the the existing one that works.

They will not talk! I'm open to suggestions.

[Controls Guy]

Could you clarify this sentence: "Once I get two switchs between the slave and master all communications stop."

Also, does the error bit assigned in the box come on?

[91dresser]

I'm speaking of the PLCs trying to talk with two managed ehternet switches between there ECOMS.

The error bit does not come on.

[91dresser]

I'm using a WX not RX.

Sorry.

[Controls Guy]

You can see the one PLC from the other location with DirectSoft, can you also see it with NetEdit?  NetEdit uses broadcast messages, which won't be retransmitted by a switch, but I don't believe DirectSoft does.  Perhaps WX uses broadcast messages as part of the exchange?  Can't imagine why it would, but who knows.  The other thing might be to check the setup of the switches themselves.

[b_carlton]

I believe an ID Number -> IP link must be set up in the ECOM itself for each remote device. Otherwise the ID number type access is a 'broadcast style' transmission.

Go to www.hosteng.com
Go to Netedit section and look in the FAQ section for FAQ0010

[91dresser]

CG: Can't see it with NetEdit from my work station because it's on a different subnet.

b_carlton: FAQ0010 appears to be for ECOMS on the same local network. I don't think it's applies to applications communicating across different subnet switches.

[Controls Guy]

I believe an ID Number -> IP link must be set up in the ECOM itself for each remote device. Otherwise the ID number type access is a 'broadcast style' transmission.

Why are those boxes addressed with a slave ID instead of an IP address, subnet, and gateway anyhow?

[franji1]

That's a limitation of the DirectLogic PLC CPU instruction set.  We're working on fixing that in a new instruction set that allows you to specify a node number OR an IP address.  However, with the current Direct Logic CPU RX/WX type instructions, all you have is a BYTE for a node number (BCD even).

[MikeS]

RX and WX instructions will us broadcasts to read and write data because the ECOM has to translate the Slave ID (0-90) in the instruction to an ethernet address. So, it sends out a packet essentially asking "is there an ECOM out there that has Module ID xx". If it gets a response, it will extract the ethernet address from the response and use that to actually process the RX or WX transaction.

You can prevent the broadcast from happening by configuring the Peer-to-Peer table in the ECOM. This table sets up the Slave ID -to- IP address lookup beforehand, so the ECOM won't have to do the broadcast, it will simply use the information in the table and send the IP packet.

[Controls Guy]

That's a limitation of the DirectLogic PLC CPU instruction set.  We're working on fixing that in a new instruction set that allows you to specify a node number OR an IP address.  However, with the current Direct Logic CPU RX/WX type instructions, all you have is a BYTE for a node number (BCD even).

Thanks.  That makes sense.

[Greg]

91dresser, some questions:
1. Is it really an H0-ECOM? Or an H0-ECOM100?
2. Do you have a peer-to-peer table configured in the master ECOM/ECOM100?
3. If you have a peer-to-peer table configured in the master ECOM/ECOM100, what are its values?
4. Are you using WX? Or ECWX?

If you do not have a peer-to-peer table configured in the master ECOM/ECOM100, and you are using WX then the ECOM/ECOM100 will indeed use a broadcast in attempts to find the slave. This broadcast telegram will not get transmitted by your switches. Thus no communication.

If you have a peer-to-peer table configured in the master and the slave is on a different subnet, then it matters what the gateway address is. The gateway on his network should know where the slave is. Another weird thing about this is that the peer-to-peer table in the master ECOM/ECOM100 needs to know the IP address of the slave and the MAC address. If, however, the slave is on a different subnet, then the IP address of the slave in the master's peer-to-peer table should indeed be the slaves IP address, however, the MAC address in the peer-to-peer configuration may need to be the MAC address of the local gateway device. I think this has to do with the way the ECOM/ECOM100 forms the packet from the information in the peer-to-peer table.

Let me know how it goes.

[91dresser]

Greg,

They are H0-ECOM100s.

I have been doing this work on my engineering workstation which is on a different subnet than the H0-ECOM100s. If I use this workstation to do the "Peer to Peer" configuration as described in manual "HX-ECOM-M" pages 3-10 & 3-11 when I click "OK" will the configuration be written down to the targeted ECOM100.

Also how do I work the "Gateway Address" into the "Peer to Peer" configuration string?

thanks,

Carl

[91dresser]

I went to the individual H0-ECOM100s with my latop, connected to them, and used NetEdit3 to program them. I have to put one of the PLCs back in it's cabinet before I know whether the issue is healed or not.

[91dresser]

They are talking! Data is being passed! Folks thanks for your suggestions/help. I would've been fighting it a lot longer without your assistance.