Is there any document anywhere that describes the communications option that can be configured with the various PM800 options, the PM800 has an RS485 port, the PM8ECC adds Ethernet and another RS485 port, then if the meter is without display a PM8RDA can be added, what we require is a document or diagram describing what would be slave and master ports in the various configurations, this has come about as we have had requests to connect to two separate masters, we have conflicting information direct from UK technical support and what we are reading on FAQ's, for example:
PM800 Series meters without the Ethernet Communications card (PM8ECC) and without the remote display adaptor (PM8RDA) have only one communication port (Comm 1) which is a 2-wire RS485 Port. When adding PM8ECC and remote display adaptor, two additional comm ports are included with these modules and they can be used in 2-wire or 4-wire mode.
When should each comm port be used? Can all 3 RS485 comm ports be used when adding a PM8ECC to a Series 800 Power Meter (PM800) with a remote display adapter?
PM800, PM820, PM850, PM870
There are three Serial Comm ports on a PM800 when PM8ECC and PM8RDA Modules are installed. A user may not know which comm port to use depending on the communications requirement.
The following serial communications ports are available on a PM800 when there is a PM8ECC and PM8RDA installed:
1. The PM800 series meter base unit has one 2-wire RS-485 port (Comm 1). RS-485 Slave Port
2. The PM800 Remote Display Module has one 4-wire RS-485 port (Comm 2). RS-485 Slave Port
3. The PM800 Ethernet Communications Card (PM8ECC) one 4-wire RS-485 port (Comm 3). RS-485 Master Port
When should each port be used?
1. The base unit 2-wire RS-485 port should be used to communicate directly with a PM800 if you have a 2-wire RS-485 daisy chain.
2. If you have a PM800 with a Remote Display module and you need to connect the PM800 to a 4-wire RS-485 daisy chain, use this communications port on the Remote Display Adapter. For a 2-wire RS-485 daisy chain you can use either port.
3. If you have a PM800 with a PM8ECC and you intend to use the Ethernet Communication card as a gateway, you will need to connect the downstream RS-485 wiring to the port on the Ethernet Communication card. This port is configurable for 2-wire or 4-wire via dip switches.
4. When the PM8ECC is added to a PM800 Meter with a remote display adapter (PM8RDA), the RS485 comm port 2 on the remote display adapter becomes disabled. Only two RS485 ports (Comm 1 and Comm 3) can be used simultaneously. COM 1 is a RS-485 Slave Port and COM 2 is a RS-485 Master port.
5. When the remote display adapter is added to a PM800 Meter without the PM8ECC, Comm 1 and Comm 2 can be used simultaneously. Both ports will require a different RS485 address (Device ID).
If you have remote display module on PM8XX, can you use 2-wire connection. For instance, one can jumper + and - terminal on RS-485 connection on remote display module. I did tried that and it did not work. Do you need to use 4 wire to 2 wire converter?
If there is no PM8ECC installed on the same PM8 meter, you should be able to use the PM8DRA's RS485 port in 2-wire connection by jumping both Tx+/Rx+ and Tx-/Rx-. The last time I used both com1 and com2 in 2-wire connection on PM8 was about half month ago, and these meters worked fine.
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