Advanced |
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| Concurrent Requests |
The following feature is new in Ignition version 8.1.0
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The number of requests that Ignition will try to send to the device at the same time. Increasing this number can sometimes help with your request throughput, however increasing this too much can overwhelm the device and negatively impact communciations with the device. |
Max Holding Registers per Request | The maximum number of Holding Registers the device can handle. Because some Modbus devices cannot handle the default of requesting 125 Holding Registers in one request, to accommodate this limitation you can change this setting.
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Max Input Registers per Request | The maximum number of Input Registers the device can handle. Because some Modbus devices cannot handle the default of requesting 125 Input Registers in one request, to accommodate this limitation you can change this setting. |
Max Coils per Request | The maximum number of Coils the device can handle. Because some Modbus devices cannot handle the default of requesting 2000 Coils in one request, to accommodate this limitation you can change this setting. |
Max Discrete Inputs per Request | The maximum number of Discrete Inputs the device can handle. Because some Modbus devices cannot handle the default of requesting 2000 Discrete Inputs in one request, to accommodate this limitation you can change this setting. |
Reverse Word Order | When reading and writing 32bit values from/to a Modbus device, the high word comes before the low word. By checking this option, the low word comes before the high word. The Modbus specification does not include a section for reading and writing 32bit values and as a result device manufacturers have implemented both methods. |
| When this option is checked, the address range for each area starts at 0. If unchecked, the range starts at 1. The Modbus specification states that Modbus addresses are to be zero based. Meaning Modbus addresses start at 0 instead of 1. To read a value from Modbus address 1024, 1023 is sent to the device. When connecting to devices that do not adhere to zero based addressing, make sure this option is not selected. |
Span Gaps | When this option is checked, it spans address gaps when optimizing requests, reducing the number of requests but increasing the amount of data requested at once. If unchecked, it does not span the address gaps. |
Allow Write Multiple Registers Request | Enable or disable Modbus function code 0x10, Write Multiple Registers. Some devices may not support this function code.
Caution: Disabling this option will break the ability to write 32-bit and String values correctly to registers.
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Force Multiple Register Writes | Force the use of Modbus function code 0x10, Write Multiple Registers, on write requests. |
Allow Write Multiple Coils Request | Enable or disable Modbus function code 0x0F, Write Multiple Coils. Some devices may not support this function code. |
Allow Read Multiple Registers Request | If disabled all registers will be read in individual read requests. Disable with caution. |
Allow Read Multiple Coils | If disabled all coils will be read in individual read requests. Disable with caution. |
Allow Read Multiple Discrete Inputs
| If disabled all discrete inputs will be read in individual read requests. Disable with caution.
Note: Function code 0x02 is always used to read Discrete Inputs, regardless what this property is set to.
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| Reconnect After Consecutive Tries | Force a reconnect after 3 consecutive timeouts. Default is true. |
Max Retry Count | Maximum number of times to retry a read request after receiving a response containing an allowable Exception Code (GatewayPathUnavailable, GatewayTargetDeviceFailToRespond, SlaveDeviceBusy, or SlaveDeviceFailure). Default is 1. |
