current loop

Greetings, O venerable All! ╔══════════════════════════════ ════════════════════════════════ ║Forwarded by Felix Knajzev ╠══════════════════════════════ ════════════════════════════════ ║Orig.Area: SU.HARDW.OTHER ║Orig.From: Vladislav Shaklein (2:5032/6.15) ║Orig.To : Dmitry Zayats (2:465/254.3) ║Orig.Subj: "current loop" ║Orig.Date: Tuesday 7 December 1999 ║Orig.Time: 18:54:00 ╚══════════════════════════════ ════════════════════════════════ =========================================== cut ========================================== Greetings, dear Dmitry! Sat Dec 04 1999 17:17, Dmitry Zayats wrote to All: DZ> Please tell me what the subject is and whether any DZ> device DZ> powered according to the current loop principle. Actually the question DZ> got in touch with DZ> with the following phrase DZ> This module is ideal for current loop powered DZ> transmitters, also known DZ> as 2-wire transmitters. === Cut [C:TMPRS-IRPS.TXT] === Current loop interface for IBM PC (c) Shaklein V.G. Novgorod 01/15/98 At the moment, almost all computers compatible with IBM PC have an RS-232 type port. However, a number of domestic devices haveinterface type "IRPS" - current loop. These interfaces are completely compatible at the protocol level and differ only in the transmission method. Thus, to control domestic devices it is enough just coordinate the hardware, and work with the software interface does not require coordination. In addition, the standard RS-232 interface ensures communication of everything up to 15 meters, and the current loop is hundreds of meters. So to connect 2 computers to each other, it is enough to connect them to each other via described adapters. This type of connection also provides galvanic decoupling between the computers used, that is, eliminates the need for them grounding when working together. 1 Active transmitter, passive receiver. Practical applications I haven't met. But I know that it happens 1.1 Transmitter ───*────#####───>+12 KT315 K/ │ K82 │/│ TxD<───#####───*───┤ │ 5K1 │ │ │ ─┴─ E │ KD522 / │ └───────> PD+ (connect to PRD+) ──┬── │ │ │ General<───────────*──────*──────────> PD- (connect to PRD-) The transistor, opening, passes current through itself, closing - allows it to flow through the receiver LED. 1.2 Receiver1─ +12 47 Ohm 4+------------│-+ │ PRD+<─####─┬──────┐ K/ | E/ ──┴── | ─┴─ --> │/ | KT361│/ KD522 / | / -->┌─┤ | ┌───┤ ──┬──2|──┬─ │ │ | │ │\n PRD-<──────┴──────┘ │ E | │ K\n +--------│----│-+ │ │ (connect AOT110B 3│ 5│ │ *─────────────────────────> RxD to PD+ └####*─────┘ │ and PD-) M11 │ │ # # #1K2 #43K Here a diode is needed for # # protection against incorrect │ │ pole lines > -12 2. Passive transmitter, active receiver. Used for connection with DVK and plotter MC6501 (aka EM7052). 2.1 Transmitter ───*────#####───>+12 KT315 K/ │ K82 │/│ TxD<───#####───*───┤ │ 5K1 │ │ │ 5 ┌──────────────> PD- ─┴─ E │ 1 +-------------│---+ (precisely MINUS) KD522 / │ └────────┐ K/ | ──┬── │ | ─┴─ │/ | │ │ | / -->┌─┤ |│ │ 2 | ─┬─ -->│ │ | General<───────────*──────*───────────┘ │ E | +---------│----│--+ AOT128 6│ 4*─────────────> PD+ └####┘ (precisely PLUS) 100K The transistor, when opening, activates the current through the optocoupler LED, and he, in turn, opens the current in the line. 2.2 Receiver ┌─#####────────────────── *────────────*───────>+12 │ 820 5│ │ │ Ohm 1 +------------│-+ │ ┌─*──────┬──────┐ K/ | E/ # ──┴── | ─┴─ --> │/ | KT361│/ 330 # KD522 / | / -->┌─┤ | ┌───┤ Ohm # ─┬─ 2| ─┬─ │ │ | │ │\n *────────┴──────┘ │ E | │ K\n │ +--------│----│-+ │ │ │ AOT128 6│ 4│ │ *────────> RxD │ └####*─────┘ │ │ M11 │ │ │ # # PRD-<────┘ # 1K2 # 43K # # PRD+<───────────────────┐ │ ││ └───────────*─────────> -12 (+ and - are NOT mixed up) General You can, of course, use AOT110B, but only 128 were on hand :-) Thus, a rule is formed: there is current - one. There is no current - zero. In the first case, there is only one LED at the receiving end (in optone), and the current through it is initiated by the transmitter. In the second case, the task of the transmitter is simply to close the circuit, and the current itself will be initiated elements located in the receiver. As a rule, the operating modes of both the transmitter and receiver can be set in devices using jumpers. For example, this possible in the IRPS block BK-0010 or the IRPS block of the MC6501 plotter. Both schemes were tested and their performance was verified. The optocouplers used (AOT110B and AOT128) provide speeds up to 9600 Baud, for higher speed it is necessary to use other optocouplers. *** WE WISH YOU SUCCESS *** All the best, Vlad. -+- GoldED/386 2.50+ + Origin: I tinker, I solder, I repair computers (2:5032/6.15) =========================================== cut ========================================== Best regards, Felix. [I.ZX]