CN113138582A - Power supply device for PLC expansion module - Google Patents

Fig. 1 (a) shows a structure in which a

10 and an

20 are connected by an

12.

The

20 receives power from the

10 through the

12 and exchanges data. Further, an expansion connector may be added to connect more expansion modules.

Fig. 1 (b) shows a structure in which the

120, 130 are connected by the expansion

150.

Therefore, in order to supplement the insufficient power, the

150 is additionally connected.

The

110 is connected to the expansion

150 through the

112, and the

120 and 130 connected to the expansion

150 receive power from the expansion

150, not from the

110.

Fig. 2 shows a more detailed block diagram of the extended

150.

The

150 includes MCU (Microcontroller Unit)

154,

156, and a direct current/direct current (DC/DC)

158.

The MCU

154 is a circuit that receives power of the MVDD voltage from the

110 and operates.

156 receives power at the CVDD voltage from DC/

158 and operates.

The DC/

158 receives external power, converts the power into a voltage used in the PLC module, and supplies power to the expansion

150 and an expansion module to be additionally connected in a later stage. For example, the DC/

158 may receive a voltage of 24V and output a voltage of 5V.

Data is also passed from the

110 to the

150 and to the

120 to which it will be later connected.

Fig. 3 shows a structure in which a leakage current is generated in such a related art extended

150.

The power generated at the DC/

158 of the

150 is transferred to the

150 and the

120. Thus, if the DC/

158 is powered down, power cannot be transferred to the

156 and the

120. The

120 may use the SN74HC244 element as a buffer and line driver for transceiving data, and the rest is constituted by the

128.

However, in the case where the DC/

158 of the

150 is powered off, the data signal may be transmitted from the

110. The data signal is passed to the

120 via the

154 or the

156. The data signal delivered to the expansion module may be re-passed to the

150 via the

122 through the power transmission line of the DC/

158. That is, a leakage current is also generated in a state where the power of the DC/

158 is turned off.

Thus, the leakage current of the data signal accidentally transmitted to the expansion

150 may cause malfunction of the expansion

150, and thus it is necessary to block the leakage current.

The

200 for PLC extension module may include

210,

220, DC/

230, and

240.

The

210, the

220, and the DC/

230 have the same configuration as the power supply device of the related art, and the

240 is added to block a leakage current.

The

240 may include a Voltage converter (Voltage Level conversion) in an open drain (open drain) mode or a Voltage converter in a push-pull (push-pull) mode.

The

240 includes first to

241, 242, 243, 244, first to

245, 246, 247, 248, first and

249, 250, first to fourth monostables (one-shot: Monostable Multivibrator) 251, 252, 253, 254, first and

255, 256, and first and

257, 258. An inverter is a logic circuit element, also called a NOT gate (NOT gate), whose output has the opposite value of the input. This inverter is a different element from a power inverter that converts direct current into alternating current.

The

257 is connected to an input of the

241, and an output of the

241 is connected to one end of the first monostable 251 and the second monostable 252 and an input of the

242.

The other end of the

251 is connected to the gate of the first MOSFET245 and the other end of the

252 is connected to the gate of the

246.

The output of the

242 is connected to one end of a

249, and the other end of the

249, the drain of the first MOSFET245, and the source of the second MOSFET246 are connected to a second data port.

The source of the first MOSFET245 is connected to the

256 and the drain of the second MOSFET246 is connected to ground, thereby forming a data signal path from the

257 to the

258.

Similarly, the

258 is connected to the input of the

243, and the output of the

243 is connected to one end of the third monostable 253, the

254, and the input of the

244.

The other end of the third monostable 253 is connected to the gate of the third MOSFET247 and the other end of the

254 is connected to the gate of the

248.

The output of the

244 is connected to one end of a

250, and the other end of the

250 is connected to the drain of the third MOSFET247, the source of the fourth MOSFET248 and the

257.

The source of the third MOSFET247 is connected to the

255 and the drain of the fourth MOSFET248 is connected to ground, thereby forming a data signal path from the

258 to the

257.

Next, a path through which data is transferred in the

240 having such a connection structure will be described in more detail.

The

240 converts the data signal input from the

257 into a data signal having a voltage of the

256, and outputs from the

258. In contrast, the data signal input from the

258 is converted into a data signal having a voltage of the

255 and output from the

257.

The

255 receives power from the PLC base unit and typically uses a voltage of 5v (mvdd). The

256 receives power from the DC/

230 and typically uses a voltage of 5v (cvdd).

Fig. 4 shows the flow of data when power is supplied to the DC/

230.

A data signal of the PLC basic unit is input from the

257. The data signal is inverted by the

241, and then input to the first MOSFET245 via the first monostable 251 and input to the second MOSFET246 via the

252.

When the input data signal is High (low), the data signal transmitted through the

241 is changed to a low (low) signal, and when the low signal is input to the first MOSFET245, which is pMOS, the first MOSFET245 is turned on (Turn-on), and the High data signal is output through the

258 at the voltage of the second

256.

In contrast, when the input data signal is low, the data signal via the

241 becomes high and only the second MOSFET246, which is an nMOS, is turned on, so the data signal via the

242 is connected to ground, and finally a low data signal is output from the

258.

Similarly, a data signal inputted from the

258 is outputted from the

257 according to the on/off of the third MOSFET247 or the

248.

Even in a state where the power of the DC/

230 is turned off, the

210 using the power of the PLC basic unit may operate, and thus a data signal may be transmitted to the

240 through the

257.

The data signal is transferred to the

251, the

252, and the

242 via the

241. However, since power cannot be transmitted from the DC/

230 to the second

256, the first MOSFET245 and the second MOSFET246 are turned off, the

242 receiving power from the second

256 is also turned off, and finally, the data signal cannot be transmitted to the

258 and is blocked.

In the opposite case, similarly, the data signal transmitted to the

258 cannot be transmitted to the

257 because the

243 receiving the power from the second

256 is in the off state.

Eventually, the following effects are produced: if the power supply of the DC/

230 is in the off state, the data signal cannot be transmitted outside the

240, and the leakage current of the data signal transmitted along the power transmission path of the DC/

230 is blocked.

1. A power supply device for a PLC expansion module is characterized by comprising:

the first data port is connected with the PLC basic unit and used for receiving and transmitting data;

the second data port is connected with the PLC expansion unit and used for receiving and transmitting data;

a first power port receiving power of a first voltage from the PLC base unit;

a DC/DC transformer for converting an external power supply into a second voltage and supplying the second voltage to the PLC expansion unit;

a second power port receiving power of a second voltage from the dc/dc transformer; and

a bidirectional voltage converter converting a signal of the first data port into a signal having the second voltage and outputting the same from the second data port, or converting a signal of the second data port into a signal having the first voltage and outputting the same from the first data port,

the second voltage is not supplied to the second power supply port when the power of the dc/dc transformer is cut off, so that the signal of the first data port is not output from the second data port.

2. The power supply device for a PLC expansion module according to claim 1,

the MOSFETs of the bi-directional voltage converter are constructed in a push-pull configuration.

3. The power supply device for a PLC expansion module according to claim 1,

the MOSFET of the bidirectional voltage converter is formed in an open-drain configuration.

4. The power supply device for a PLC expansion module according to claim 1,

the bidirectional voltage converter includes first to fourth inverters, first to fourth MOSFETs, first and second resistors, and first to fourth monostables, the first and third MOSFETs being p-type MOSFETs, the second and fourth MOSFETs being n-type MOSFETs,

when the power of the DC/DC transformer is cut off and the power is not supplied to the second power port, the signal of the first data port is not transferred to the second data port.

5. The power supply device for a PLC expansion module according to claim 4,

the first data port is connected with the input of the first inverter, the output of the first inverter is connected with one end of the first monostable, one end of the second monostable and the input of the second inverter, the other end of the first monostable is connected with the grid electrode of the first MOSFET, the other end of the second monostable is connected with the grid electrode of the second MOSFET, the output of the second inverter is connected with one end of the first resistor, the other end of the first resistor, the drain electrode of the first MOSFET and the source electrode of the second MOSFET are connected with the second data port, the source electrode of the first MOSFET is connected with the second power supply port, and the drain electrode of the second MOSFET is connected with the ground.

6. The power supply device for a PLC expansion module according to claim 4,

the second data port is connected with the input of the third inverter, the output of the third inverter is connected with one ends of the third monostable and the fourth monostable and the input of the fourth inverter, the other end of the third monostable is connected with the grid electrode of the third MOSFET, the other end of the fourth monostable is connected with the grid electrode of the fourth MOSFET, the output of the fourth inverter is connected with one end of the second resistor, the other end of the second resistor, the drain electrode of the third MOSFET and the source electrode of the fourth MOSFET are connected with the first data port, the source electrode of the third MOSFET is connected with the first power supply port, and the drain electrode of the second MOSFET is connected with the ground.