SYNC Control Guidelines
SYNC mode is useful to prevent cross-talk between sensors in close proximity. The simplest configuration has one master and one slave sensor, a common situation when two sensors are used in one machine such as a converting slitter-rewinder. Larger SYNC groups can have up to 31 slave sensors that can be organized in up to five time slots (phases). In applications with multiple sensors, such as measuring across a conveyor belt to determine material flow volume, using multiple phases assures the sensors are properly spaced in both position and time to prevent crosstalk. A SYNC group has ONLY ONE master sensor, which measures on phase 1 and can be configured to provide slave commands from one to five phases.
Each slave is configured to measure on one of the phases. If only one phase is used the master and the slave sensor(s) will measure simultaneously (assuming the slave sensor(s) is configured for phase 1). If more than one phase is used, as determined by the master sensor, each slave sensor must be configured to one of the operational phases. Two-phase configuration can be set with either the sensor push-button or SenixVIEW software. SenixVIEW must be used to set 1, 3, 4 or 5 phase setups.
Up to 32 sensors can be connected in a master-slave network. When a master is operational, SYNC mode consumes the serial data network and Modbus serial data communications by external means such as SenixVIEW is not possible, but the analog and switch outputs function normally and update at each sensor’s phase time. If the master sensor is disconnected or taken out of master operation the slaves will stop measuring. Slaves that lose the master input can have their analog and switch outputs assume default states as defined by SenixVIEW’s “No SYNC” parameter value for each output.
A more useful benefit of disabling the master is that Modbus communications is restored to the group. SenixVIEW can then connect with all sensors in the SYNC group using the Group Control feature. In fact, Group Control will automatically suspend the master sensor so that the entire sensor group can be configured, saved and/or restored from a backup. These capabilities are possible if all the sensors in the group are first configured with individual Modbus addresses.
The serial data bus configuration of all sensors in SYNC mode is RS-485, whether using an RS-485 or RS-232 sensor model. We recommend using RS-485 sensor models for simplicity and to avoid the need to switch data interfaces when using RS-232 sensors in different modes. The RS-232 models will revert to RS-232 if a sensor’s SYNC function is deactivated.
The more phases in play, the slower the overall measurement function since the master has to instruct all phases in succession. The Measurement Interval value determines the rate at which the master controls the phases. General guidelines:
- Every sensor in the SYNC network should have its own network address within the range of 1-247
- All sensors must use the same BAUD rate
- The SYNC 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