modbusOpenX (Function)

Architecture:	X32 / NX32 / NX32L
Firmware version:	4.50 / 1.00.00

This function will open a connection to a MODBUS network.

The connection uses either the RTU, ASCII or TCP protocol.

The device supports both master mode, where the device controls the MODBUS network and polls the slaves, and slave mode, where the device waits for commands from the master.

Please note that the TCP protocol can only be used via the LAN network interface, which must be opened before communication is possible.

For NX32L devices, all interfaces can be used with the TCP protocol (from firmware version 1.08.00).

Input:

mode : SINT

1	- RTU protocol
2	- ASCII protocol
3	- TCP protocol

unit_id : INT (0..247)

The address of the RTCU device on the MODBUS network.

If this parameter is set to zero, the RTCU device will be the master on the network.

port : DINT (default -1)

When port is set to -1, the default port for the selected mode is used.

	mode = 1	Selects which serial port to use (see serial port enumeration, default is port 0).
	mode = 2	Selects which serial port to use (see serial port enumeration, default is port 0).
	mode = 3	Selects which IP port to listen for connections from Masters on. (default is port 502)

iface : SINT (default 0)

The network interface from which incoming TCP connections are accepted. (See Network)

The network interface must be present and connected, when modbusOpenX is called if set.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

(from firmware version 1.32.00).

con_timeout : UINT (0..30000) (default 1000)

The number of milliseconds to try to connect to a slave before timing out.

This parameter is ignored if mode != 3 or if the RTCU device is not the master.

baud : DINT (9600,19200,38400,57600,115200) (default 115200)

Selects the desired baud rate.

This parameter is ignored if mode 3 is selected.

bit : SINT (7/8) (default 8)

Selects the number of bits per character.

This parameter is ignored if mode 3 is selected.

Note: 7 bit without parity bit only works on LX devices.

parity : SINT (0..2) (default 1)

Selects the desired parity, 0 is none, 1 is even, and 2 is odd.

This parameter is ignored if mode 3 is selected.

stopbit : SINT (1/2) (default 1)

Selects number of stop bits.

This parameter is ignored if mode 3 is selected.

Note: Only 1 stop bit is supported on the RS485 ports on NX devices.

rs485 : SINT (-1..1) (default -1)

-1	- Auto detect. First try to use RS485 then RS232.
0	- Use RS232
1	- Use RS485

This parameter is ignored if mode 3 is selected.

allow1 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow2 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow3 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow4 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow5 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow6 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow7 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow8 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow9 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

allow10 : DINT (default 0)

Remote IP address accepted. 0 if all is allowed.

This parameter is ignored if mode != 3 or if the RTCU device is the master.

Returns: INT

ID of the MODBUS connection.

-1	- All MODBUS connections are in use.
-2	- Illegal unit_id selected.
-5	- Illegal serial port.
-6	- Failed to open connection.
-7	- Illegal serial port parameters.
-8	- Illegal mode selected.
-9	- The network interface is not connected.

Declaration:

FUNCTION modbusOpenX : INT;
VAR_INPUT
   mode    : SINT;
   unit_id : INT;
   port    : DINT := -1;
   iface   : SINT := 0;
   con_timeout : UINT := 1000;
   baud    : DINT := 115200;
   bit     : SINT := 8;
   parity  : SINT := 1;
   stopbit : SINT := 1;
   rs485   : SINT := -1;
   allow1  : DINT := 0;
   allow2  : DINT := 0;
   allow3  : DINT := 0;
   allow4  : DINT := 0;
   allow5  : DINT := 0;
   allow6  : DINT := 0;
   allow7  : DINT := 0;
   allow8  : DINT := 0;
   allow9  : DINT := 0;
   allow10 : DINT := 0;
END_VAR;

Example:

INCLUDE rtcu.inc

VAR
   mbNet : INT;
   mbRcv : modbusReceive;
END_VAR;

FUNCTION setINT;
VAR_INPUT
   adr : PTR;
   v   : INT;
END_VAR;
   memcpy(dst := adr + 1, src := ADDR(v)    , len := 1);
   memcpy(dst := adr    , src := ADDR(v) + 1, len := 1);
END_FUNCTION;

FUNCTION_BLOCK modbusReadDiscreteInputs;
VAR_INPUT
   net_id  : INT;
   unit_id : INT;
   index   : INT;
   length  : INT;
END_VAR;
VAR_OUTPUT
   status : INT;
   size   : INT;
   input  : ARRAY[1..32] OF BOOL;
END_VAR;
VAR
   rc, i  : INT;
   buf    : ARRAY[1..253] OF SINT;
   mask   : SINT;
END_VAR;

   // Check length
   IF length < 1 OR length > 32 THEN
      status := 1;
      RETURN;
   END_IF;
   IF index < 1 THEN
      status := 2;
      RETURN;
   END_IF;

   // Build command
   buf[1] := 16#02;
   setINT(adr := ADDR(buf[2]), v := index - 1);
   setINT(adr := ADDR(buf[4]), v := length);

   // Send command
   rc := modbusSend(net_id := net_id, unit_id := unit_id, frame := ADDR(buf), size := 5);
   IF rc <> 0 THEN
      status := 3;
      RETURN;
   END_IF;

   // Wait for reply
   IF NOT modbusWaitData(net_id := net_id, timeout := 5000) THEN
      status := 4;
      RETURN;
   END_IF;

   // Read reply
   mbRcv(net_id := net_id, frame := ADDR(buf), maxsize := SIZEOF(buf));
   IF mbRcv.status <> 0 THEN
      status := 5;
      RETURN;
   END_IF;
   IF mbRcv.unit_id <> unit_id THEN
      status := 6;
      RETURN;
   END_IF;
   IF buf[1] <> 16#02 THEN
      status := 7;
      RETURN;
   END_IF;

   // Parse reply
   mask := 1;
   FOR i := 1 TO length DO
      input[i] := BOOL(buf[3 + ((i - 1) / 8)] AND mask);
      mask := shl8(in := mask, n := 1);
      IF mask = 0 THEN mask := 1; END_IF;
   END_FOR;
   size   := length;
   status := 0;
END_FUNCTION_BLOCK;

PROGRAM ModbusExample;
VAR
   dinRead : modbusReadDiscreteInputs;
   linsec  : DINT;
   i       : INT;
END_VAR;

   DebugMsg(message := "Initializing...");
   mbNet := modbusOpenX(mode := 1, unit_id := 0, port := 2, baud := 19200, parity := 0);
   DebugFmt(message := "modbus...\1", v1 := mbNet);

BEGIN
   IF clockNow() > linsec THEN
      DebugMsg(message := "------------------------------");
      DebugMsg(message := "Reading inputs:");
      dinRead(net_id := mbNet, unit_id := 9, index := 1, length := 4);
      DebugFmt(message := "-status=\1", v1 := dinRead.status);
      IF dinRead.status = 0 THEN
         FOR i := 1 TO dinRead.size DO
            DebugFmt(message := "-input[\1]=\2", v1 := i, v2 := INT(dinRead.input[i]));
         END_FOR;
      END_IF;
      // Set next reading
      linsec := clockNow() + 5;
   END_IF;
END;
END_PROGRAM;