Application Note IntelliSense Application Note 3 Messaging between Bimba IntelliSense SIM Module and Siemens S7-1200 PLC
Table of Contents INTRODUCTION... 3 HARDWARE SETUP.... 3 MODBUS RTU CONFIGURATION.... 4 MODBUS DATA LAYOUT... 5 02/24/15 rev1.0 2
Introduction This application note is intended to be used in conjunction with sample code file App_Note_S7_1200_ CM_1200 and serves as an example for basic Modbus RTU communication. The main hardware used for this example was a Siemens S7-1200 PLC, Bimba IntelliSense Starter Kit (ISK-SMA_), with a Bimba IntelliSense Junction Block (ISH-R04). The Siemens sample code MODBUS_RTU_V11 SP2 Upd5 was used as a programing template, and the Siemens manual s71200_system_manual_en-us_en-us.pdf was used for reference. Hardware Setup For this example, a 2-wire RS-485 Modbus network was implemented using the IntelliSense Junction Block. SIM DIP switches 5 and 6 were set high to tie the RX/TX terminals together. DIP switch 7 was also set high to enable the internal 150 ohm terminating resistor. Power for the SIM unit was supplied using pins 7 and 8 of the junction block. (Wire colors are not representative of actual cable.) 02/24/15 rev1.0 3
Modbus RTU Configuration Modbus RTU is a serial Master-Slave protocol. This means the Master device (PLC in this case) controls when each Slave device on the network acts upon the Master s commands. Only one Slave device can transmit back to the Master at a time. There can be a maximum of 32 devices on a RS485 Modbus RTU network. The IntelliSense SIM unit is capable of utilizing a variety of 8 bit serial communication configurations. A baud rate of 9,600 bps, no-parity, 8 bit, and 1 stop bit configuration was set in the SIM. The CM- 1241 module was set for half-duplex (2-wire) mode in the properties section of the module. All other communication settings are set when the program runs. See Network 1 for Communications Initialize block. You may adjust these settings for your application, but the settings must match on all devices on the Modbus RTU network. Keep in mind the Modbus Master assumes the address value of 0. CM-1241 Module IntelliSense SIM 02/24/15 rev1.0 4
Modbus Data Layout The Modbus RTU protocol defines how the data registers of a Modbus device are laid out. The IntelliSense SIM unit currently only utilizes Holding Registers. 0x = Coil = 00001-09999 1x = Discrete Input = 10001-19999 3x = Input Register = 30001-39999 4x = Holding Register = 40001-49999 The Holding Registers of the IntelliSense SIM units are defined using the following table: Register Description Size 40001 Pressure of port 1 in absolute tenths of PSIa 2 Bytes 40002 Pressure of port 2 in absolute tenths of PSIa 2 Bytes 40003 Ambient pressure in absolute tenths of PSIa 2 Bytes 40004 Pressure of port 1 in absolute tenths of mbar 2 Bytes 40005 Pressure of port 2 in absolute tenths of mbar 2 Bytes 40006 Ambient pressure in absolute tenths of mbar 2 Bytes 40007 Line pressure in absolute tenths of PSIa 2 Bytes 40008 Line pressure in absolute tenths of mbar 2 Bytes 40009 Rod Position 2 Bytes 40010 Time in ms for last extension event 2 Bytes 40011 Time in ms for last retraction event 2 Bytes 40012 Temperature of port 1 in hundredths of a F 2 Bytes 40013 Temperature of port 2 in hundredths of a F 2 Bytes 40014 Temperature of port 1 in hundredths of a C 2 Bytes 40015 Temperature of port 2 in hundredths of a C 2 Bytes 40016 Cycle count, low word 2 Bytes 40017 Cycle count, high word 2 Bytes 40018 Cycle count limit, low word 2 Bytes 40019 Cycle count limit, high word 2 Bytes 40020 First two bytes of SIM revision 2 Bytes 40021 Second two bytes of SIM revision 2 Bytes 40022 Sensor Status 2 Bytes Bit 0-1 Streaming Bit 1-2 Streaming Bit 3-1 Recognized Bit 4-2 Recognized 40023 Pressure Failure 2 Bytes Bit 0 - Line Pressure High Bit 1 - Line Pressure Low Bit 2 - Sensor 1 Pressure High Bit 3 - Sensor 1 Pressure Low Bit 4 - Sensor 1 Pressure High Bit 5 - Sensor 1 Pressure Low Register Description Size 40024 Leakage Failure 2 Bytes Bit 0 - Rear Piston Seal Bit 1 - Front Piston Seal Bit 2 - Rod Seal 40025 Temperature Failure 2 Bytes Bit 0-1 Temp High Bit 1-1 Temp Low Bit 2-2 Temp High Bit 3-2 Temp Low 40026 Extent Failure 2 Bytes Bit 0 - Extend Time High Bit 1 - Extend Time Low Bit 2 - Retract Time High Bit 3 - Retract Time Low 40027 Estimated Life Remaining above 90% - Bit 0 Estimated Life Remaining below 10% - Bit 1 2 Bytes 40028 Estimated Life Remaining Percentage between 90 and 10 Decimal value 2 Bytes 40029 Life Expected Thresholds 2 Bytes Bit 0 - Yellow Light Threshold Bit 1 - Red Light Threshold 40030 Estimated Cycles remaining, low word 2 Bytes 40031 Estimated Cycles remaining, high word 2 Bytes 40032 Estimated Days Remaining 2 Bytes 40501 RTC Seconds 2 Bytes 40502 RTC Minutes 2 Bytes 40503 RTC Hours (24hr) 2 Bytes 40504 RTC Hours (12hr) 2 Bytes 40505 RTC AM/PM 2 Bytes 40506 RTC Day 2 Bytes 40507 RTC Month 2 Bytes 40508 RTC Year (last 2 digits) 2 Bytes 40510 ID 1 String 60 Bytes 40540 ID 2 String 40 Bytes 40560 Part Number 30 Bytes 02/24/15 rev1.0 5
A Modbus Master transmits function codes to specific Modbus Slave addresses. Each function has its own code number: 01 Read Coils 02 Read Discrete Inputs 03 Read Holding Registers 04 Read Input Register 05 Write Single Coil 06 Write Single Register The IntelliSense SIM module only supports the Read Holding Register (function 3). This function code allows you to poll the network Slave for the current values in a single register or a consecutive series of registers using a single command. For this example, two (2) message requests are sent to Slave address 1. The first request polls registers 1-32 and the second requests the same data. This could easily be adjusted to poll multiple SIMs. Comms Initialization 02/24/15 rev1.0 6
Message 1 Setup Message 2 Setup 02/24/15 rev1.0 7
The values returned from the SIM unit are configured to populated integer register DB3.DBX6.0 Master_ data.receive. This example solution can be adapted for increased message requests to include multiple Modbus Slave addresses. After copying networks 6-7 and pasting them after the current rung seven (7), change the In value of the MOV instruction located on rung seven (7) to the next consecutive message step, and adjust the three (3) new EQU conditions so that the compared value is equal to the new message step value. Keep in mind the new message instruction will have to be setup with the Data Table Address in the PLC, number of elements, beginning location of data registers being polled, and correct Slave address. 02/24/15 rev1.0 8