Does hardwiring not require a communication protocol?
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1. With the system hardwired to the DCS, is it no longer necessary to use communication protocols? 2. Also, can DCS only use one communication protocol? Can PROFIBUS and MODBUS not coexist?
The only communication protocol that can be transmitted via hardwiring is HART communication, which can be transmitted through analog signal circuits. With other digital communication methods, due to differences in the amplitude and frequency of the bit pulses as well as the communication protocols, it is not possible to transmit multiple protocols in the same circuit, unless those protocols are compatible with each other.
1. Do you mean by hard wiring that a single signal is connected directly to the channel of the I/O module? If so, there’s no need for a communication protocol! 2. If it’s not the I/O module, then it must be the communication module; different communication modules should allow for separate protocol settings!
1. You should know that hardwired connections use analog signals, and these signals are standardized by IEC, namely 4–20 mA and 1–5 V. The so-called communication protocol is a superimposed signal loaded onto the standard signal by manufacturers to facilitate communication with smart meters. Therefore, a communication protocol is not necessary; however, smart meters generally come equipped with such protocols to facilitate debugging between cabinets. Currently, the main protocols in use are Rosemount’s HART, Yokogawa’s BRAIN, and Honeywell’s DE. 2. DCS has many communication interfaces, allowing it to support a variety of different communication protocols, as it is not possible to ensure that all the instruments and devices that communicate with the DCS use the same protocol. But if you ask whether a single signal line can accommodate both PROFIBUS and MODBUS simultaneously, the answer is definitely no – different protocols have different parsing methods, and using them together would lead to conflicts
1. It’s not necessary, but some communication protocols such as HART can be added.
2. Different communication protocol modules on the DCS can handle various communication protocols, but a single cable can only support one communication protocol