C R O S S   A U T O M A T I O N  . . . .  A P P L I C A T I O N   N O T E S 

Industry: Plastics (Vacuum Molding)
Overview: Our client, an OEM, had purchased various components from Cross Automation and other sources. They were having difficulty integrating the components with each other after assembly on-site and required assistance in getting the equipment up and running. The customer had purchased eight Watlow Anafase temperature controllers  and needed to communicate from those controllers to a Parker CTC P3 PowerStation HMI  using Modbus RTU protocol.
Discovery

By going on-site Cross Automation was able to discover the following information.

  • The manufacturer’s configuration software (running on a Laptop PC) and cable (with integrated converter) would communicate to the temperature controllers

  • The P3 PowerStation would not communicate to the temperature controllers, or to a single temperature controller connected directly to it.

  • The OEM had not set the COM port (COM 2) correctly

  • The OEM had wired the communications cable from the temperature controllers  to the P3 correctly.

  •  A Laptop PC running Interact and communicating to a temperature  controller using the manufacturer’s cable did communicate correctly. 

    

Challenges
  • The End User was pressuring the OEM to commission the equipment ASAP.
  • The manufacturer of the temperature controllers had been unable to help the OEM with the communications problem. The temperature controllers worked with the manufacturer’s configuration software and cabling.
System Solutions
  • By testing the various components, it was determined that all the hardware was in proper working order. The temperature controllers could communicate to a Laptop PC running either the configuration software or Interact using the Watlow provided cable and adapter
  • Watlow’s documentation showed the temperature controllers communicating using a RS 485 protocol. The documentation also showed the temperature controller communication wiring as 4 wire RS 485. Dissection of the Watlow cable and adapter revealed that the documentation was incorrect. The actual configuration of the adapter was RS 422 instead of RS 485.
  • By changing the configuration of the com port on the CTC P3 from RS 485 to RS 422 communication to the temperature controllers was established. However other communication problems remained.
  • After reviewing the Watlow documentation yet again, we found that the Modbus offsets in the P3 were set incorrectly. After correcting these offsets the CTC P3 communicated properly to the temperature controllers
 Customer Benefits

By providing knowledgeable technical support at the OEM’s installation site, Cross Automation was able to solve the communications problem in a timely manner.  The OEM was then able to complete the installation and get the end user’s equipment up and running on schedule.

Cross Automation was able to solidify the relationship with the OEM by providing timely on-site assistance.

 

 

P3 Com Port Setup

Interact settings for ModBus driver

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P3 Com Port Setup

Com Port 2 set for RS 422

 Com Port 2 wiring diagram

P3 DB 9                                                     RJ12 Jack on Anafase Temp Controller

1    TXD -                                                  5          RX -

2    TXD +                                                 2          RX +

3    RXD +                                                 3          TX +

4    RXD -                                                  4          TX -

5    Signal Ground                                       1          Common

6    DSR

7    RTS 

8    CTS

9    RI

 

 

 

 

Interact settings for ModBus driver

CPU 984

Protocol RTU

Baud 192000

Parity Even

Stop Bits 1

Com Port Com 2

Acquisition Rate Constant

Message Timeout 20

Wait for Writes? No

Write Buffer 10

Disabled

Start Offset 0

ASCII Terminator 0

ASCII Length 2