1.16 Output Functions¶

All output functions are internally created from the same output function. Understanding the output function is important for using any output block. This is also necessary for creating specialized outputs using the Advanced Output function.

The output functions can be in three different states — OFF, ON, and ERROR — and can only go to the ON-state from the OFF-state. A logical 1 on the ON input connector drives the function to the ON-state, if no external errors have been detected and if all other criteria are met, which are discussed further in this chapter.

Figure 1.74 — OSSD Output in OFF-state, outputting 0V on pins 1 and 3

Figure 1.74: OSSD Output in OFF-state, outputting 0V on pins 1 and 3.

Figure 1.75 — OSSD Output in ON-state, outputting an OSSD signal on pins 1 and 3

Figure 1.75: OSSD Output in ON-state, outputting an OSSD signal on pins 1 and 3.

When the function is in the OFF-state, the terminals try to output the defined OFF-state signals on their pins (the OFF-state signals can be any output signal type; all signal types are described in 1.16.4 Output signal types). In most cases this is 0V, however it is possible to have any signal type as the OFF-state. In the ON-state the terminals output the ON-state signal.

If a terminal reads a different signal from the one it is trying to output, it means there is an external error (for example a short circuit), and the function will go to the ERROR-state.

1.16.1 Name¶

It is recommended to give a unique name for every input and output function. Input and output function blocks have a setting Name that can be set by the user to identify the input/output function. The identifier name is displayed on the block in the logic editor. When generating the project report, the input and output identifier names are shown for each function so the user can easily identify the function.

Figure 1.76 — An OSSD output with its Name set to "Machine 1"

Figure 1.76: An OSSD output with its Name set to "Machine 1".

1.16.2 ERROR-state¶

In the ERROR-state, the terminals that have detected an error will output 0V, regardless of the configured OFF-state signal on that terminal (the OFF-state could be an active signal). The pins that have not detected an error will output their OFF-state signal. The terminals that have detected an error will keep outputting 0V until the function leaves the ERROR-state. The function will leave the ERROR-state when all external faults have disappeared (if the Reset ERROR input is not enabled).

Figure 1.77 — OSSD Output in ERROR-state due to an external error on terminal 12 (short circuit to 24V)

Figure 1.77: OSSD Output in ERROR-state due to an external error on terminal 12 (short circuit to 24V).

Figure 1.78 — When the external error disappears, the output goes to ON-state again

Figure 1.78: When the external error disappears, the output goes to ON-state again.

Enabling the Reset ERROR input changes this behavior. If the Reset ERROR input is enabled, the function will stay in the ERROR-state when all external errors have disappeared, until a logical 1 is given on the Reset ERROR input. If the Reset ERROR input is not enabled, the function leaves the ERROR-state as soon as all external errors have disappeared.

Note

The Reset ERROR input does not require a flank to reset the error. A constant logical 1 is enough.

Note

The Reset ERROR input cannot be used as a reset function for the ON signal. If no ERROR has been detected, the output will go to the ON-state as soon as the ON input gets a logical 1, regardless of the signal received on the Reset ERROR input.

Setting the Reset ERROR input to a constant logical 1 will result in the same function as disabling the Reset ERROR input (without the Reset ERROR signal, the output is always reset after errors).

Figure 1.79 — OSSD Output where the Reset ERROR input is enabled

Figure 1.79: OSSD Output where the Reset ERROR input is enabled. The function will not leave the ERROR-state until a logical 1 is received on the Reset ERROR input after the external errors have disappeared.

1.16.3 Feedback¶

When the Feedback input is enabled, the function can only go to the ON-state when a high flank (0→1) is received on the ON input and the Feedback input is a logical 1. If the Feedback input is 0, the function will go to the ERROR-state until the ON signal goes to logical 0 and the error is reset by the Reset ERROR signal (if enabled). If the function is in the ON-state and an external error is detected, then when leaving the ERROR-state the function cannot go to the ON-state again until the ON signal has gotten a logical 0 and then a 1.

Fatal errors can be reset by the touch button on the LED panel. If the cause of the fatal error is gone, it will not jump into fatal error after reset.

1.16.4 Output signal types¶

The following sections describe all available output signal types that can be configured for a terminal.

1.16.4.1 VDC¶

The VDC signal is a constant high signal. The output voltage is the power supply voltage to the unit depending on load, minus 0.5V. When outputting a VDC signal, the terminal can never detect a short circuit to another type of signal. A short circuit directly to 0V/ground will trigger the over-current protection and the unit will go to the fatal ERROR-state.

1.16.4.2 0V¶

The 0V signal is a constant low signal.

1.16.4.3 OSSD¶

A terminal configured with OSSD will output an OSSD signal. An OSSD signal will have short interruptions (less than 0.15 ms) to check if there is an external short circuit to the input. During the interruption the output shall go down to 0V. Short circuits to fixed voltage and to other OSSD outputs in the same unit can be detected. OSSD outputs are not recommended for capacitive loads.

1.16.4.4 A, B, C, D Pulses¶

The A/B/C/D pulse is a coded signal that can be used as an input in the same unit. A short circuit to fixed voltage, or to any other A/B/C/D pulse or inverted A/B/C/D pulse in the same unit, is detected on all outputs and inputs.

1.16.4.5 Inverted A, B, C, D Pulses¶

The inverted A/B/C/D pulse is a coded signal that can be used as an input in the same unit. The inverted A/B/C/D pulses are the inverted versions of the A/B/C/D pulses. A short circuit to fixed voltage, or to any other A/B/C/D pulse or inverted A/B/C/D pulse in the same unit, is detected on all outputs and inputs.

1.16.5 The Advanced Output function block¶

The Advanced Output block can be used for creating a specialized output function. 1–8 channels can be used and configured freely. The output can use relay outputs and transistor outputs in the same function. Any signal types can be used for the ON and OFF-state.