Sensor Synchronization: A Step-by-Step Guide

SYNCH Control Guidelines

SenixVIEW sensor configuration software allows up to 32 sensors to be synchronized in a master-slave network. In SenixVIEW, SYNCH mode is useful to prevent sensor interference from sensors located close to one another by alternating sensor measurement cycles. It is also useful to acquire simultaneous measurements over an area using a grid of sensors by causing all sensors to measure at the same time. In the latter case, greater precision can be obtained by using a higher baud rate than the default 9600 Baud. Baud refers to the communication data rate.

In SYNCH, there can be up to 31 slaves organized in up to five phases with any number of sensors in each phase. There can only be ONE MASTER to a SYNCH group and it measures on phase one. The more phases in play, the slower the overall measurement function since the master has to instruct all phases in succession. The Interval value determines the rate at which the master controls the phases.

  • Every sensor in the SYNCH network must have its own network address within the range of 1-247 inclusive
  • All sensors must use the same BAUD rate
  • The SYNCH network operates on RS-485 communication protocol
  • All sensors in an RS-485 network have their yellow and gray wires connected (bussed)
  • All sensors must share a common ground (blue) wire

Sensors configured for RS-232 protocol can be used in a SYNCH network, however their configuration is switched to RS-485 during setup. RS-485 supports multi-addressable networking, while RS-232 does not. Once a RS-232 sensor is configured as a SYNCH master or slave, RS-485 communication equipment must be used to connect to it individually through SenixVIEW. Therefore, RS-485 sensors are recommended to start with. A modified sensor with a pushbutton can be returned to its RS-232 configuration by use of the pushbutton and the TEACH 15 command.

Step-by-step instructions for using the SYNCH feature in a network.

Step 1: Master Setup and Network Address Setting

a. Determine which sensor will be the master. Connect only it to the PC using SenixVIEW.

b. Determine the network address it will have. All new sensors are at address 1.

c. Under the menu item Sensor choose Communications. There you can assign a new address in the range of 1-247 inclusive.

i. SenixVIEW will disconnect and reconnect at the new address.

d. Navigate to the Measure tool screen. Under “Measurement Activation” choose the SYNCH Master that matches the number of phases you intend to use. For example:

i. If you want all sensors firing at one time, choose “SYNCH Master 1-Phase”.

ii. If you want your sensors grouped to measure in 4 groups, choose “SYNCH Master 4-Phases”.

iii. If you want your sensors to measure in a repeating sequence, such as 123-123-123, choose “SYNCH Master 3-phase”.

iv. Do not choose a SYNCH Master phase less than the number of phases you intend to have.

e. Close the Measurements tool dialog. You will see a warning screen advising you that if you are connected to an RS-232 sensor it is about to become RS-485 and you will lose the ability to communicate unless you switch to RS-485 style interface equipment. This is why it is better to begin with all RS-485 sensors. To return a sensor to its default (non-SYNCH) configuration, see section H below.

f. Disconnect the master sensor from SenixVIEW.

Step 2: Slave Setup

a. Connect to a sensor which will become a SYNCH slave using the proper equipment (RS-232 or RS-485 according to its label). The sensor should be the ONLY sensor on the network at this point.

b. Set its network address as above.

c. Choose its SYNCH slave phase.

i. Choose a DIFFERENT network address for each sensor. No duplicates allowed.

i. On the Measurements tool dialog, pull down “Measurement Activation” and choose the slave phase.

ii. Choose 1 if you want it to measure in phase 1 with the master.

iii. Choose 2—5 if you want it to measure at one of the alternate phases.

iv. Don’t choose a phase number higher than the master phase number or it will never measure.

d. Close the Measurements tool dialog. Observe the warning screen noted above in 1) e.D.

e. Disconnect the slave from SenixVIEW. Remove sensor from the network.

f. Repeat steps F—I for each slave.

i. Do not duplicate a network address.

Step 3: Connecting the RS-485 Network

a. Wire all network sensors together. This can be done by wiring between terminal boards with shielded twisted pair cable.

i. Connect the slave sensor gray wires together.

ii. Connect slave sensor yellow wires together

iii. The blue reference (GND) must also be extended to every sensor

iv. Connect the Master’s gray, yellow, and blue to the network

v. Every sensor must have a unique network ID at this point and be set for the same Baud rate. If not, see section H

vi. Connect the PC to the network using RS-485 interface equipment

b. Make any regular analog output connections to external equipment as needed.

Step 4: Starting SYNCH Operation

a. Supply 15-30VDC to every sensor

c. All sensors begin once powered. Slave sensors are triggered by the Master only

d. No serial data communication is possible using SenixVIEW because the Master controls the bus

e. Analog and switch outputs are active while in SYNCH mode

f. The synched sensor group will operate in SYNCH mode.

g. While in SYNCH mode, individual communication is not possible unless the “Master SYNCH OFF” button is clicked. See the following section

Step 5: Pausing SYNCH Operation to communicate with individual sensors or the group using RS-485 equipment

a. Open SenixVIEW>Sensor> Group Control

b. In Group Control, click “Master SYNCH OFF”.

c. In the Connect dialog box, enter the Network Address of any sensor in the group.

d. Click Connect. Import the sensor setup to the Workspace when asked.

e. Make any changes to the sensor while in the Workspace. Upload the Workspace to the Sensor by right-clicking the WorkSpace icon and dragging it over the Sensor icon.

Step 6: To restore SYNCH operation once it has been suspended

a. Open SenixVIEW>Sensor> Group Control

b. Using RS-485 communication equipment, do a Scan for Sensors to display every sensor on the network and its address. Every sensor in the group should be displayed in the Sensor List area by address and configuration.

vii. If not, check wiring and review network addresses. No duplicates allowed.

viii. A slave blinking red/green is not in communication with a master.

ix. Only RS-485 sensors will be displayed.

x. Click “Master SYNCH ON” to restart the synchronized mode operation led by the SYNCH Master.

Step 7: Stopping SYNCH Operation

a. In Group Control, click “Master SYNCH OFF”.

Step 8: Taking a sensor out of SYNCH mode

a. Stop SYNCH operation, as above

b. Connect to the selected sensor using RS-485 communication equipment

c. Navigate to the Measurements dialog and choose “Continuous” from the Measurement Activation

d. Close the Measurements dialog and upload the Workspace to the sensor.

e. Note: Any RS-232 sensor that had been automatically changed to RS-485 while in SYNCH mode pull down menu will automatically revert to RS-232 at this time. It will communicate using RS-232 communication equipment

Step 9: Alternate method without SenixVIEW:

a. On a push-button model, use a TEACH-15 command

  1. i. Unlock the TEACH mode by holding the button for 3 flashes and releasing
  2. ii. LED will flash slowly indicating TEACH mode invoked
  3. iii. Hold the button for 15 flashes then release to cancel SYNCH master or slave mode
  4. iv. Hold button for 3 flashes and release to stop TEACH mode, or cycle power, or simply wait 15 minutes

Step 10: Note, after leaving SYNCH MODE:

a. Any RS-232 sensor that had been automatically changed to RS-485 while in SYNCH mode will automatically revert to RS-232 at this time. It will communicate using RS-232 communication equipment

b. Remove any RS-232 sensor from the network. RS-232 only supports one sensor at a time.