Can ION 7650 COM1 and COM2 daisy chain 2 serial RS485 devices?

[sesa74337_bridg]

Hi, I would like to know if I can put 2 daisy-chain on 1 ION7650 Comm Cards?

As we know, ION7650 has COM 1 and COM2 on it's network card, both of them can be configured to RS485. For example, if I have 20 NSX Circuit Breakers, 4 Power Meters,  my questions are:

(1) Can I put 10 NSX Circuit Breakers and 2 Power Meters on COM1 and another 10 NSX CB plus 2 Power Meters on COM2? (Like the EGX400 and make sure all 24 devices have unique IDs)

(2) The Comm card only has 1 IP address, do I need to add the site twice in MC with different names?

(3) Compared with putting all 24 devices onto 1 daisychain, how's the Performance for splitting them into 2 Com ports?

Thanks,

James Rong

[patrickw · Accepted solution]

Hi James,

You can indeed use both COM1 and COM2 in Ethergate mode on a single 7550/7650 (also 7550RTU, 8600, 8650, 8800).  Each RS485 chain is limited only by the RS485 bus itself, 31 slave devices per chain without the use of repeaters.

The meter uses different ports to differentiate the two ports, so the COM1 Ethergate will be on port 7801, and the COM2 Ethergate will be on port 7802.  You do need to setup two sites in MC for this.

With the split chain, the poll rate will be faster since while one chain is waiting for serial response, the other chain can still service requests.

[BrianB]

Hi James,

I moved your post into the newly created Hardware Power Monitoring Community, as this forum was created solely for the purpose of answering metering hardware and firmware questions.

Feel free to post wihtin this community should there be any other questions that arise.

Brian

[sesa74337_bridg]

Hi, Patrick,

Thanks for your reply. One more question is the Port 502, when do we need to use that port? Is that when we doing modbus mastering (Mapping Slave Modbus devices)?

Cheers,

James Rong

[sesa74337_bridg]

Thanks, Brian,

Cheers

James

[jimbradley]

Hi,

Just be aware that Ethergate mode is not a Modbus TCP/IP > Modbus RTU translator like the EGX100/300. 

It is a simple protocol translator where a data packet of any type is wrapped in a TCP/IP packet and resent on the serial port.  There is a chance of messages being routed out of sequence as Modbus RTU does not have a message count as part of the protocol.

The ION 7x50 can be configured as a Modbus TCP/IP > Modbus RTU translator but I believe it only supports 1 port in this mode.

Jim

[sesa74337_bridg]

Thanks, Jim,

If I want to configure the ION 7x50 as a Modbus TCP/IP to Modbus RTU translator, for example, attach 10 NSX circuit breakers and 2 PM5350 on COM1, does that mean I need to create modbus register map in the ION7650 framwork for NSX CBs and PM5350?

[jimbradley]

Hi James,

To set the Modbus TCP/IP to Modbus RTU gateway you do not need to configure a register map.  That is needed when the ION7x50 is the Modbus Master.  For the Gateway functionality you need to configure the Modbus Master Options Module and set up which Com port is going to be the Modbus Gateway.  This is covered in the ION7550 /ION 7650 User Guide (doc # 70002-0248-07) at page 115.

Jim

[MarthaV]

Hi Jame

in the case of an ION7330 what it will be the limit of the daysi chain using this meter as ethergate.

i have two PM820 two PM750 1 PM200 nad 9 IEM3255, can i connect all this meters thru the EtherGate ??

[BrianB]

The installation guide shows a max of 32 devices.

Please also keep in mind that Comm 2 is the hardwired Ethergate port.