Eaton MTL5501-SR Instruction Manual

Also see for MTL5501-SR: Instruction manual

Contents

INM 5500 Rev 107110 3 2 Hazardous-area interfacingDisplays/terminals: For details of interfacing with MTL640 and MTL650 displays/terminals (asan alternative to the MTL696 communications interface) see the appropriate product instructionmanual.Table 10 2MTL5051TerminalsMTL640modeMTL650modeCommsmodeOther ISdevices1 Common Common Common Common2 V signal 12V - 5V/12V3 I return Rx Rx -4 - Tx Tx -5 - - - Tx6 - - - RxSwitch1a On Off Off Off1b On On On Off/OnTable 10 3Terminals RS232 mode TTL mode RS422 mode7 - - Rx-8 - - Rx+9 - Tx Tx+10 Tx - Tx-11 Common Common Common12 Rx Rx -13 Supply -ve Supply -ve Supply -ve14 Supply +ve Supply +ve Supply +veSwitch2a Off On On2b On Off OffAcross hazardous areas: For communication across hazardous areas MTL5051 devices are usedin pairs to transfer bi-directional full duplex data across hazardous areas, as shown in figure10.4. Current switching is used to minimise the bandwidth-limiting effects of long cables.The maximum baud rate in this mode is the lesser of 19.2k baud or the cable-related rateproduced by the following formula.Remote signalling baud rate formula, for back-to-back mode across a hazardous area:max baud rate = K/(RxCxL2)where K = 0.25 (constant)R = cable resistance (Ω/m)C = cable capacitance (F/m)L = length (m)For example, with a 2km cable of 100pF/m capacitance and 40mΩ/m resistance, the maximumbaud rate = 0.25/(40mΩ x 100pFx 2km2) = 15k baud. This assumes that the cable is 2 coresplus screen, with the screen used for the ‘common’ connection.RS232-level devices: Communication with RS232-level interfaces, such as a suitably certifiedIS keyboard, mouse, etc, is achieved by using one or more MTL5051 units as required by the ISdevice.(TTL level interfaces are accommodated by the TTL compatibility of RS232 receivers.)The supply to IS equipment at terminal 2 can be set to either 5V or 12V, by a switch located ontop of the unit, as follows:+12V mode 12.0V ±5% (load <23mA)+12V mode 8.0V min (load >23mA to <50mA)+5V mode5.6V ±5% (load >23mA to <50mA)Note: the normal RS232 limitations of bandwidth versus cable length are applicable. As a ruleof thumb, speed (baud) x length (metres) <150,000.Figure 10 5:Top labelfor MTL5051