Communications Port Configuration

The Communications Port Configuration for any module containing communications ports is accessed from the Hardware Configuration window. For example, to access the P3-550 communications port configuration, first select the Local Base Group from the Hardware Configuration window by double left-clicking the Local Base Group or by right-clicking the Local Base Group and selecting Open from the drop down menu as seen below.

Then select the P3-550 by double left-clicking the CPU or by right-clicking the CPU and selecting Open from the drop down list. This will display the P3-550 configuration window.

The P3-550 window will open as shown below. Although the following descriptions will focus on the P3-550 communications ports, the settings also apply to any other module containing these ports.

1. Options Tab: Click on this Tab to go to the Options dialog.
2. Remote Access Tab: Click on this Tab to go to the Remote Access Configuration dialog.
3. Serial Ports Tab: Click on this Tab to go to the Serial Ports Configuration dialog.

Ethernet Configuration

Ethernet Ports: There are two 10/100Base-T Ethernet ports on most Productivity CPU's. P3-530 and P1-540 CPUs only have the External Ethernet port.

• External Ethernet: The upper (P3 and P1) or forward (P2) Ethernet port is referred to as the "External Ethernet Port". This port can connect to Modbus TCP Client devices, Modbus TCP Server devices and PCs running the Productivity Suite programming software. The External Ethernet Port is configured with an IP Address, Subnet Mask and Default Gateway, allowing it to function seamlessly on a typical LAN network.
• Local Ethernet: The lower Ethernet (Remote I/O)port is referred to as the “Local Ethernet Port”. This port functions as a Productivity Suite Remote I/O Client and also as a GS-Drive Client. The Local Ethernet Port is not configurable and each CPU Remote I/O network should be located on its own physical or logical network.

Note: Two CPU Remote I/O networks cannot co-exist on the same LAN.

External Ethernet Port Settings

4. Port Name: Allows the entry of a unique Name for the External Ethernet Port.  This Name is referenced in the Communications instructions (MRX, MWX, RX, WX) to select the Port to send the request from.
5. Port Security Option: This Option can be used as a simple Security measure to prevent Modbus TCP write requests from being accepted by the CPU.  To allow Reads and Writes, select Read/Write.
6. TCP/IP Settings: The IP Setting of this Port may be changed in several ways:

• The Settings may be entered manually in the Choose CPU tool in the Productivity Suite programming software.  This allows the user to make changes to the IP to allow connection by the computer running the Productivity Suite programming software.  Changes are sent using Multicast Messages.
• The Settings can be saved as part of the project.  This must be Enabled in the P3-550 Hardware Configuration Settings by selecting Use the Following (discussed on Item f below).  If handled this way, the Settings stored in the project will take effect at Project Transfer and at boot up only.  The Settings may be changed after boot up.

7. Use Current Settings: When selected, Project Transfer or boot up will not make changes to the TCP/IP Settings of the CPU.
8. Use DHCP: This specifies that the CPU should request its IP Settings from a DHCP Server on the network.

Note: If the CPU is set to use DHCP for it's IP Settings it cannot, in all likelihood, be used as a Modbus TCP Server.

9. Use The Following: If this Option is selected, the CPU will set itself to the specified project Settings upon Project Transfer or at boot up.
10. IP Address: This field is where the IP Address is specified in Four Octets.
    For Example:  192.168.1.5
11. Subnet Mask: This field is where the Subnet Mask is specified in Four Octets (i.e., 255.255.255.0 ).  The Subnet Mask is used in conjunction with the IP Address to configure a Logical Network.
12. Default Gateway: This field is where the Default Gateway Address is specified in Four Octets (i.e., 192.168.1.1).  This is typically the IP Address of the router on the network.  If a target IP Address is specified in an outgoing message from the CPU that is not in the Local Subnet, the Default Gateway Address is where this message will be sent.
13. A DNS (Domain Name Service) server is a computer server that contains a database of public IP addresses and their associated hostnames, and in most cases, serves to resolve, or translate, those common names to IP addresses as requested. In easier to understand terms: A DNS server on the internet is the device that translates the www.automationdirect.com you type in your browser to the 205.151.114.26 IP address that it really is. You can configure two DNS servers in case one of them happens to fail, after which the device will resort to using the secondary server.

Note: Other names for a DNS server include name server, nameserver, and domain name system server.

14. Preferred DNS Server IP Address: the TCP/IP Address of the first DNS server to contact for resolving the Name to an IP Address.
15. Alternate DNS Server IP Address: the TCIP/IP Address of an alternate DNS server to contact if the preferred DNS server cannot resolve the Name to an IP Address.
16. Timeout Between Data Query and Response: The Time period specified in this field is the Time between the queries sent from the CPU (via a Communication instruction, such as a MRX, MWX, RX or WX) and the Time a response from that device is received.  If the Response takes longer to receive (or is not received) than the specified Time period, a Timeout Error will occur for the given instruction.  Each instruction has a Timeout Status bit that can be assigned to it.  See the diagram shown below.

17. Modbus TCP Port: This is the listening TCP Port Number for Modbus TCP connections.  If necessary, this value can be adjusted for advanced router access.  In most situations, this Number should be left at 502.
18. Comm Heartbeat Value: This feature allows the ladder logic in the CPU to know if a device has stopped communicating to the CPU.  If a value is placed in this field, the CPU will start a timer between each communication packet coming in to the CPU.  If a communication packet fails to be received by the CPU within the specified time period, the Module Status Bit (MST)Ethernet Heartbeat Timeout Bit will become true.

Remote Access Configuration

1. Options Tab: Click on this Tab to go to the Options dialog.

2. Ethernet Ports Tab: Click on this Tab to go to the Ethernet Ports Configuration dialog.

3. Serial Ports Tab: Click on this Tab to go to the Serial Ports Configuration dialog.
4. Web Server Function: Allows the ability to make a non secure web connection to the P3-550 in order to access the USB pen drive and view read-only system tags. When enabled, a port number selection is required.
   1. Port: (Default 80) Allows user to set a port number ranging from 1-65535.

5. Session Timeout: Allows the user to set a specific time limit (1-20 mins.) on inactivity that will close the Web Server connection. If there is no activity between the PC and the Web Server for the specified time limit, the connection will close.

6. Mobile Function: Enables Remote Access which allows the CPU Data Remote Monitor App to monitor the selected tags.

7. Password Option: Allows the user to set a password for Remote Access using the CPU Data App or access to the Web Server.

   • Enter an account name & password of up to a combination of 16 numbers and characters (can include special characters).

Serial Configuration

When the Serial Ports Tab is selected, the Serial Ports settings are displayed as shown below.

There are two Serial Ports on the Productivity CPUs.  Both Ports are capable of Modbus RTU Client (device that initiates communications requests) and Server (device that responds to communications requests) communications.  They are also capable of ASCII outgoing strings and incoming strings.

1. Options Tab: Click on this Tab to go to the Options dialog.
2. Ethernet Ports Tab: Click on this Tab to go to the Ethernet Ports Configuration dialog.
3. Remote Access Tab: Click on this Tab to go to the Remote Access Configuration dialog.

RS-232 & RS-485 Port Settings

4. Port Name: Allows the entry of a unique Name for the RS-232 and RS-485 Ports. This name is referenced inside of the Communications instructions (MRX, MWX, RX, WX) and ASCII instructions (AIN, AOUT, CPO, CPI) to select the Port to send or receive the request.
5. Port Security:ThisOptioncan be used as a simple Security measure to prevent Modbus TCP write requests from being accepted by theCPU. To allowReadsandWrites, selectRead/Write.
6. Protocol: This field determines whether the Port is used for Modbus RTU communications, sending or receiving ASCII Strings or performing the Custom Protocol function.
7. Baud Rate: Choose the Baud Rate that your device and the CPU should communicate in this field. The appropriate choice will vary greatly with device, application and environment.  The important point is that all devices communicating on the network need to be set to the same Baud Rate.  The available BaudRates are 1200, 2400, 9600, 19200, 33600, 38400, 57600 and 115200 bp.
8. Node Address: This field is used only when the CPU is a Modbus RTU Server device.  This field is used to uniquely identify the CPU on the network.  This setting is also sometimes referred to as a Station Address.  This field can be set from 1 to 247.
9. Parity: The Parity Bit is used as a simple, low-level form of Error Detection. All devices on the network need to be at the same Parity setting. The appropriate choice will vary with devices. Valid selections are None, Even and Odd.
10. Data Bits: This field determines whether the communications packet uses Seven Data Bits or Eight Data Bits. Eight Data Bits is the only valid selection for Modbus RTU.  Either Seven or Eight Data Bits can be selected when using ASCII communications. Set this field to match the device that is connected to the CPU.
11. Stop Bits: This field determines whether the communications packet uses One or Two Stop Bits.  Set this field to match the device that is connected to the CPU.
12. RTS Off Delay Time (RS-232 Only): This Time period is the amount of Time between the end of the data transmission to when the RTS signal is turned off.  The diagram below illustrates this.  This setting may be needed when using media converters (RS-232 to RS-422/485 converters) and/or radio modems.  A delay may be needed at the end of the data transmission for processing time in the devices.

13. RTS On Delay Time (RS-232 Only): This Time period is the amount of Time between when the RTS Signal is turned ON and the data transmission begins.  The diagram below illustrates this. This setting may be needed when using media converters (RS-232 to RS-485 converters) and/or radio modems.  A delay may be needed after the assertion of the RTS Signal and when the data transmission begins for processing time in the device.

14. Timeout Between Query and Response: The Time period specified in this field is the Time between the queries sent from the CPU (via a Communication instruction, such as an MRX, MWX, RX, or WX) and the Time a Response from that device is Received.  If the Response takes longer to receive (or is not received) than the specified Time period, a Timeout Error will occur for the given instruction.  Each instruction has a Timeout Status bit that can be assigned to it.

15. Modbus Character Timeout: The Modbus Character Delay Time is specified as the Time between two bytes (or characters) within a given Modbus Message.  The Modbus RTU specification states that this time must be no more than 1.5 Character Times (real time based on Baud Rate).  Sometimes delays do occur between bytes when using radio modems, media converters, etc.  This setting allows some tolerance in these situations for the incoming Modbus Messages in the CPU.  The CPU will wait for the amount of time specified in this field before discarding the incomplete packet.  If the CPU does not receive the remainder of the Message within the specified TimeFrame, it will discard the first portion of the Message and wait for a new Message.

16. Response/Request Delay (RS-485 Only):  This setting is used when the CPU is a Modbus RTU Server or Client on the RS-485 Port.

    The total Response Time can be up to the Total CPU Scan Time + the Value specified in this field. When using 2-wire RS-485 communications, sometimes Echoes can occur since both devices use the same differential signal pair to send and receive.

• If acting as a Server, upon receiving a Modbus Request, the CPU will wait for the time period specified in this field before sending a Response. This can be used with slow clients that need extra time to change from sending to receiving.

• If acting as a Client, after receiving a Modbus Response, the CPU will wait for the time period specified in this field before sending another Request. This can be used to delay request messages in order to give extra time for slow server devices.

17. Comm Heartbeat Value: This feature allows the ladder logic in the CPU to know if a device has stopped communicating to the CPU.  If a value is placed in this field, the CPU will start a timer between each communication packet coming in to the CPU.  If a communication packet fails to be received by the CPU within the specified Time period, the System Bit RS-232 Heartbeat Timeout Bit or RS-485 Heartbeat Timeout Bit will become true.