CIF11 Modbus Slave

[cyrus]

Hi dears 

I have one CP1H CPU and CIF11 option port on it.

CP1H will be slave and I want to use modbus slave function. (ABB is Master and CIF11 is slave)

I check the logic with modbus poll and i didnt have any Receive from CIF11.

I have some questions:

1- which terminal in CIF11 must be used? SDA+,SDA- or RDA+,RDA- ( I use Modbus RS485 two wire )

2- I mounted CIF11 on port 2 and in setting of port 2 I Choose RS-232C in Mode, Stop bit=1, parity=none , Data bit=8. is there another settings?

3- I set CIF11 DIP switches ( ON,ON,ON,OFF,OFF,ON) is it OK?

4-I change 4,5 DIP Switches to ON in CP1H.

 

Thanks

[DanW]

1)  For your information, Modbus is inherently half duplex because the Master has to wait for the slave to process its request and then reply.  Therefore masters are (almost) never programmed to take advantage of full duplex operation for Modbus because it's too complex and statistically not worthy of the effort.

4 wire RS-485 is for full duplex operation.

2 wire RS-485 is for half duplex operation.

If you can configure it, use half duplex for Modbus.

2)  Connections to convert 4 wire (full duplex) to 2 wire (half duplex) historically jumpered  the (-) together:  Rx- jumpered to Tx- and the (+) drivers were jumpered:  Rx+ jumpered to Tx+

However, on a recently purchased USB/RS-485 converter (FTDI chipset), I found it would not communicate when I jumpered it like I've done for years.  When I removed the jumpers and used only 2 terminals, it operated OK.   So some experimentation might be needed for half duplex operation from a device capable of 4 wire full duplex operation.

3)  I have no familiarity with either ABB or Omron, so I'm confused about choosing RS-232 for port 2.   The SDA+, SDA-, RDA+, RDA- designations are 4 wire RS-485 designations, not RS-232.   If you are using port 2 for RS-485 communiations, then you can't configure the port for RS-232.  RS-232 is not compatible with RS-485 without a hardware converter. 

 

[cyrus]

6 hours ago, DanW said:

1)  For your information, Modbus is inherently half duplex because the Master has to wait for the slave to process its request and then reply.  Therefore masters are (almost) never programmed to take advantage of full duplex operation for Modbus because it's too complex and statistically not worthy of the effort.

4 wire RS-485 is for full duplex operation.

2 wire RS-485 is for half duplex operation.

If you can configure it, use half duplex for Modbus.

2)  Connections to convert 4 wire (full duplex) to 2 wire (half duplex) historically jumpered  the (-) together:  Rx- jumpered to Tx- and the (+) drivers were jumpered:  Rx+ jumpered to Tx+

However, on a recently purchased USB/RS-485 converter (FTDI chipset), I found it would not communicate when I jumpered it like I've done for years.  When I removed the jumpers and used only 2 terminals, it operated OK.   So some experimentation might be needed for half duplex operation from a device capable of 4 wire full duplex operation.

3)  I have no familiarity with either ABB or Omron, so I'm confused about choosing RS-232 for port 2.   The SDA+, SDA-, RDA+, RDA- designations are 4 wire RS-485 designations, not RS-232.   If you are using port 2 for RS-485 communiations, then you can't configure the port for RS-232.  RS-232 is not compatible with RS-485 without a hardware converter. 

 

Thank you for your respone

i solved my problem

all of cpu dip switches must be off

RS232 mode for cif11 is ok

this mode means no protocol in this option board setting

other setting must be ok